class BigDecimal
BigDecimal
provides arbitrary-precision floating point decimal arithmetic.
Introduction¶ ↑
Ruby provides built-in support for arbitrary precision integer arithmetic.
For example:
42**13 #=> 1265437718438866624512
BigDecimal
provides similar support for very large or very accurate floating point numbers.
Decimal arithmetic is also useful for general calculation, because it provides the correct answers people expect–whereas normal binary floating point arithmetic often introduces subtle errors because of the conversion between base 10 and base 2.
For example, try:
sum = 0 10_000.times do sum = sum + 0.0001 end print sum #=> 0.9999999999999062
and contrast with the output from:
require 'bigdecimal' sum = BigDecimal("0") 10_000.times do sum = sum + BigDecimal("0.0001") end print sum #=> 0.1E1
Similarly:
(BigDecimal("1.2") - BigDecimal("1.0")) == BigDecimal("0.2") #=> true (1.2 - 1.0) == 0.2 #=> false
A Note About Precision¶ ↑
For a calculation using a BigDecimal and another value
, the precision of the result depends on the type of value
:
-
If
value
is a Float, the precision is Float::DIG + 1. -
If
value
is a Rational, the precision is larger than Float::DIG + 1. -
If
value
is a BigDecimal, the precision isvalue
‘s precision in the internal representation, which is platform-dependent. -
If
value
is other object, the precision is determined by the result of +BigDecimal(value)+.
Special features of accurate decimal arithmetic¶ ↑
Because BigDecimal
is more accurate than normal binary floating point arithmetic, it requires some special values.
Infinity¶ ↑
BigDecimal
sometimes needs to return infinity, for example if you divide a value by zero.
BigDecimal("1.0") / BigDecimal("0.0") #=> Infinity BigDecimal("-1.0") / BigDecimal("0.0") #=> -Infinity
You can represent infinite numbers to BigDecimal
using the strings 'Infinity'
, '+Infinity'
and '-Infinity'
(case-sensitive)
Not a Number¶ ↑
When a computation results in an undefined value, the special value NaN
(for ‘not a number’) is returned.
Example:
BigDecimal("0.0") / BigDecimal("0.0") #=> NaN
You can also create undefined values.
NaN is never considered to be the same as any other value, even NaN itself:
n = BigDecimal('NaN') n == 0.0 #=> false n == n #=> false
Positive and negative zero¶ ↑
If a computation results in a value which is too small to be represented as a BigDecimal
within the currently specified limits of precision, zero must be returned.
If the value which is too small to be represented is negative, a BigDecimal
value of negative zero is returned.
BigDecimal("1.0") / BigDecimal("-Infinity") #=> -0.0
If the value is positive, a value of positive zero is returned.
BigDecimal("1.0") / BigDecimal("Infinity") #=> 0.0
(See BigDecimal.mode
for how to specify limits of precision.)
Note that -0.0
and 0.0
are considered to be the same for the purposes of comparison.
Note also that in mathematics, there is no particular concept of negative or positive zero; true mathematical zero has no sign.
bigdecimal/util¶ ↑
When you require bigdecimal/util
, the to_d
method will be available on BigDecimal
and the native Integer
, Float
, Rational
, and String
classes:
require 'bigdecimal/util' 42.to_d # => 0.42e2 0.5.to_d # => 0.5e0 (2/3r).to_d(3) # => 0.667e0 "0.5".to_d # => 0.5e0
Methods for Working with JSON¶ ↑
-
::json_create: Returns a new BigDecimal object constructed from the given object.
-
#as_json: Returns a 2-element hash representing
self
. -
#to_json: Returns a JSON string representing
self
.
These methods are provided by the JSON gem. To make these methods available:
require 'json/add/bigdecimal'
Copyright © 2002 by Shigeo Kobayashi <shigeo@tinyforest.gr.jp>.
BigDecimal
is released under the Ruby and 2-clause BSD licenses. See LICENSE.txt for details.
Maintained by mrkn <mrkn@mrkn.jp> and ruby-core members.
Documented by zzak <zachary@zacharyscott.net>, mathew <meta@pobox.com>, and many other contributors.
Constants
- BASE
Base value used in internal calculations. On a 32 bit system,
BASE
is 10000, indicating that calculation is done in groups of 4 digits. (If it were larger, BASE**2 wouldn’t fit in 32 bits, so you couldn’t guarantee that two groups could always be multiplied together without overflow.)- EXCEPTION_ALL
Determines whether overflow, underflow or zero divide result in an exception being thrown. See
BigDecimal.mode
.- EXCEPTION_INFINITY
Determines what happens when the result of a computation is infinity. See
BigDecimal.mode
.- EXCEPTION_NaN
Determines what happens when the result of a computation is not a number (NaN). See
BigDecimal.mode
.- EXCEPTION_OVERFLOW
Determines what happens when the result of a computation is an overflow (a result too large to be represented). See
BigDecimal.mode
.- EXCEPTION_UNDERFLOW
Determines what happens when the result of a computation is an underflow (a result too small to be represented). See
BigDecimal.mode
.- EXCEPTION_ZERODIVIDE
Determines what happens when a division by zero is performed. See
BigDecimal.mode
.- INFINITY
Special value constants
- NAN
- ROUND_CEILING
Round towards +Infinity. See
BigDecimal.mode
.- ROUND_DOWN
Indicates that values should be rounded towards zero. See
BigDecimal.mode
.- ROUND_FLOOR
Round towards -Infinity. See
BigDecimal.mode
.- ROUND_HALF_DOWN
Indicates that digits >= 6 should be rounded up, others rounded down. See
BigDecimal.mode
.- ROUND_HALF_EVEN
Round towards the even neighbor. See
BigDecimal.mode
.- ROUND_HALF_UP
Indicates that digits >= 5 should be rounded up, others rounded down. See
BigDecimal.mode
.- ROUND_MODE
Determines what happens when a result must be rounded in order to fit in the appropriate number of significant digits. See
BigDecimal.mode
.- ROUND_UP
Indicates that values should be rounded away from zero. See
BigDecimal.mode
.- SIGN_NEGATIVE_FINITE
Indicates that a value is negative and finite. See
BigDecimal.sign
.- SIGN_NEGATIVE_INFINITE
Indicates that a value is negative and infinite. See
BigDecimal.sign
.- SIGN_NEGATIVE_ZERO
Indicates that a value is -0. See
BigDecimal.sign
.- SIGN_NaN
Indicates that a value is not a number. See
BigDecimal.sign
.- SIGN_POSITIVE_FINITE
Indicates that a value is positive and finite. See
BigDecimal.sign
.- SIGN_POSITIVE_INFINITE
Indicates that a value is positive and infinite. See
BigDecimal.sign
.- SIGN_POSITIVE_ZERO
Indicates that a value is +0. See
BigDecimal.sign
.- VERSION
The version of bigdecimal library
Public Class Methods
Internal method used to provide marshalling support. See the Marshal module.
static VALUE BigDecimal_load(VALUE self, VALUE str) { ENTER(2); Real *pv; unsigned char *pch; unsigned char ch; unsigned long m=0; pch = (unsigned char *)StringValueCStr(str); /* First get max prec */ while((*pch) != (unsigned char)'\0' && (ch = *pch++) != (unsigned char)':') { if(!ISDIGIT(ch)) { rb_raise(rb_eTypeError, "load failed: invalid character in the marshaled string"); } m = m*10 + (unsigned long)(ch-'0'); } if (m > VpBaseFig()) m -= VpBaseFig(); GUARD_OBJ(pv, VpNewRbClass(m, (char *)pch, self, true, true)); m /= VpBaseFig(); if (m && pv->MaxPrec > m) { pv->MaxPrec = m+1; } return VpCheckGetValue(pv); }
inline VALUE BigDecimal_double_fig(VALUE self) { return INT2FIX(VpDblFig()); }
static VALUE BigDecimal_s_interpret_loosely(VALUE klass, VALUE str) { char const *c_str = StringValueCStr(str); Real *vp = VpNewRbClass(0, c_str, klass, false, true); if (!vp) return Qnil; else return VpCheckGetValue(vp); }
Limit the number of significant digits in newly created BigDecimal
numbers to the specified value. Rounding is performed as necessary, as specified by BigDecimal.mode
.
A limit of 0, the default, means no upper limit.
The limit specified by this method takes less priority over any limit specified to instance methods such as ceil, floor, truncate, or round.
static VALUE BigDecimal_limit(int argc, VALUE *argv, VALUE self) { VALUE nFig; VALUE nCur = SIZET2NUM(VpGetPrecLimit()); if (rb_scan_args(argc, argv, "01", &nFig) == 1) { int nf; if (NIL_P(nFig)) return nCur; nf = NUM2INT(nFig); if (nf < 0) { rb_raise(rb_eArgError, "argument must be positive"); } VpSetPrecLimit(nf); } return nCur; }
Returns an integer representing the mode settings for exception handling and rounding.
These modes control exception handling:
-
BigDecimal::EXCEPTION_NaN.
-
BigDecimal::EXCEPTION_INFINITY.
-
BigDecimal::EXCEPTION_UNDERFLOW.
-
BigDecimal::EXCEPTION_OVERFLOW.
-
BigDecimal::EXCEPTION_ZERODIVIDE.
-
BigDecimal::EXCEPTION_ALL.
Values for setting
for exception handling:
-
true
: sets the givenmode
totrue
. -
false
: sets the givenmode
tofalse
. -
nil
: does not modify the mode settings.
You can use method BigDecimal.save_exception_mode
to temporarily change, and then automatically restore, exception modes.
For clarity, some examples below begin by setting all exception modes to false
.
This mode controls the way rounding is to be performed:
-
BigDecimal::ROUND_MODE
You can use method BigDecimal.save_rounding_mode
to temporarily change, and then automatically restore, the rounding mode.
NaNs
Mode BigDecimal::EXCEPTION_NaN controls behavior when a BigDecimal NaN is created.
Settings:
-
false
(default): ReturnsBigDecimal('NaN')
. -
true
: Raises FloatDomainError.
Examples:
BigDecimal.mode(BigDecimal::EXCEPTION_ALL, false) # => 0 BigDecimal('NaN') # => NaN BigDecimal.mode(BigDecimal::EXCEPTION_NaN, true) # => 2 BigDecimal('NaN') # Raises FloatDomainError
Infinities
Mode BigDecimal::EXCEPTION_INFINITY controls behavior when a BigDecimal Infinity or -Infinity is created. Settings:
-
false
(default): ReturnsBigDecimal('Infinity')
orBigDecimal('-Infinity')
. -
true
: Raises FloatDomainError.
Examples:
BigDecimal.mode(BigDecimal::EXCEPTION_ALL, false) # => 0 BigDecimal('Infinity') # => Infinity BigDecimal('-Infinity') # => -Infinity BigDecimal.mode(BigDecimal::EXCEPTION_INFINITY, true) # => 1 BigDecimal('Infinity') # Raises FloatDomainError BigDecimal('-Infinity') # Raises FloatDomainError
Underflow
Mode BigDecimal::EXCEPTION_UNDERFLOW controls behavior when a BigDecimal underflow occurs. Settings:
-
false
(default): ReturnsBigDecimal('0')
orBigDecimal('-Infinity')
. -
true
: Raises FloatDomainError.
Examples:
BigDecimal.mode(BigDecimal::EXCEPTION_ALL, false) # => 0 def flow_under x = BigDecimal('0.1') 100.times { x *= x } end flow_under # => 100 BigDecimal.mode(BigDecimal::EXCEPTION_UNDERFLOW, true) # => 4 flow_under # Raises FloatDomainError
Overflow
Mode BigDecimal::EXCEPTION_OVERFLOW controls behavior when a BigDecimal overflow occurs. Settings:
-
false
(default): ReturnsBigDecimal('Infinity')
orBigDecimal('-Infinity')
. -
true
: Raises FloatDomainError.
Examples:
BigDecimal.mode(BigDecimal::EXCEPTION_ALL, false) # => 0 def flow_over x = BigDecimal('10') 100.times { x *= x } end flow_over # => 100 BigDecimal.mode(BigDecimal::EXCEPTION_OVERFLOW, true) # => 1 flow_over # Raises FloatDomainError
Zero Division
Mode BigDecimal::EXCEPTION_ZERODIVIDE controls behavior when a zero-division occurs. Settings:
-
false
(default): ReturnsBigDecimal('Infinity')
orBigDecimal('-Infinity')
. -
true
: Raises FloatDomainError.
Examples:
BigDecimal.mode(BigDecimal::EXCEPTION_ALL, false) # => 0 one = BigDecimal('1') zero = BigDecimal('0') one / zero # => Infinity BigDecimal.mode(BigDecimal::EXCEPTION_ZERODIVIDE, true) # => 16 one / zero # Raises FloatDomainError
All Exceptions
Mode BigDecimal::EXCEPTION_ALL controls all of the above:
BigDecimal.mode(BigDecimal::EXCEPTION_ALL, false) # => 0 BigDecimal.mode(BigDecimal::EXCEPTION_ALL, true) # => 23
Rounding
Mode BigDecimal::ROUND_MODE controls the way rounding is to be performed; its setting
values are:
-
ROUND_UP
: Round away from zero. Aliased as:up
. -
ROUND_DOWN
: Round toward zero. Aliased as:down
and:truncate
. -
ROUND_HALF_UP
: Round toward the nearest neighbor; if the neighbors are equidistant, round away from zero. Aliased as:half_up
and:default
. -
ROUND_HALF_DOWN
: Round toward the nearest neighbor; if the neighbors are equidistant, round toward zero. Aliased as:half_down
. -
ROUND_HALF_EVEN
(Banker’s rounding): Round toward the nearest neighbor; if the neighbors are equidistant, round toward the even neighbor. Aliased as:half_even
and:banker
. -
ROUND_CEILING
: Round toward positive infinity. Aliased as:ceiling
and:ceil
. -
ROUND_FLOOR
: Round toward negative infinity. Aliased as:floor:
.
static VALUE BigDecimal_mode(int argc, VALUE *argv, VALUE self) { VALUE which; VALUE val; unsigned long f,fo; rb_scan_args(argc, argv, "11", &which, &val); f = (unsigned long)NUM2INT(which); if (f & VP_EXCEPTION_ALL) { /* Exception mode setting */ fo = VpGetException(); if (val == Qnil) return INT2FIX(fo); if (val != Qfalse && val!=Qtrue) { rb_raise(rb_eArgError, "second argument must be true or false"); return Qnil; /* Not reached */ } if (f & VP_EXCEPTION_INFINITY) { VpSetException((unsigned short)((val == Qtrue) ? (fo | VP_EXCEPTION_INFINITY) : (fo & (~VP_EXCEPTION_INFINITY)))); } fo = VpGetException(); if (f & VP_EXCEPTION_NaN) { VpSetException((unsigned short)((val == Qtrue) ? (fo | VP_EXCEPTION_NaN) : (fo & (~VP_EXCEPTION_NaN)))); } fo = VpGetException(); if (f & VP_EXCEPTION_UNDERFLOW) { VpSetException((unsigned short)((val == Qtrue) ? (fo | VP_EXCEPTION_UNDERFLOW) : (fo & (~VP_EXCEPTION_UNDERFLOW)))); } fo = VpGetException(); if(f & VP_EXCEPTION_ZERODIVIDE) { VpSetException((unsigned short)((val == Qtrue) ? (fo | VP_EXCEPTION_ZERODIVIDE) : (fo & (~VP_EXCEPTION_ZERODIVIDE)))); } fo = VpGetException(); return INT2FIX(fo); } if (VP_ROUND_MODE == f) { /* Rounding mode setting */ unsigned short sw; fo = VpGetRoundMode(); if (NIL_P(val)) return INT2FIX(fo); sw = check_rounding_mode(val); fo = VpSetRoundMode(sw); return INT2FIX(fo); } rb_raise(rb_eTypeError, "first argument for BigDecimal.mode invalid"); return Qnil; }
Execute the provided block, but preserve the exception mode
BigDecimal.save_exception_mode do BigDecimal.mode(BigDecimal::EXCEPTION_OVERFLOW, false) BigDecimal.mode(BigDecimal::EXCEPTION_NaN, false) BigDecimal(BigDecimal('Infinity')) BigDecimal(BigDecimal('-Infinity')) BigDecimal(BigDecimal('NaN')) end
For use with the BigDecimal::EXCEPTION_*
See BigDecimal.mode
static VALUE BigDecimal_save_exception_mode(VALUE self) { unsigned short const exception_mode = VpGetException(); int state; VALUE ret = rb_protect(rb_yield, Qnil, &state); VpSetException(exception_mode); if (state) rb_jump_tag(state); return ret; }
Execute the provided block, but preserve the precision limit
BigDecimal.limit(100) puts BigDecimal.limit BigDecimal.save_limit do BigDecimal.limit(200) puts BigDecimal.limit end puts BigDecimal.limit
static VALUE BigDecimal_save_limit(VALUE self) { size_t const limit = VpGetPrecLimit(); int state; VALUE ret = rb_protect(rb_yield, Qnil, &state); VpSetPrecLimit(limit); if (state) rb_jump_tag(state); return ret; }
Execute the provided block, but preserve the rounding mode
BigDecimal.save_rounding_mode do BigDecimal.mode(BigDecimal::ROUND_MODE, :up) puts BigDecimal.mode(BigDecimal::ROUND_MODE) end
For use with the BigDecimal::ROUND_*
See BigDecimal.mode
static VALUE BigDecimal_save_rounding_mode(VALUE self) { unsigned short const round_mode = VpGetRoundMode(); int state; VALUE ret = rb_protect(rb_yield, Qnil, &state); VpSetRoundMode(round_mode); if (state) rb_jump_tag(state); return ret; }
Public Instance Methods
Returns the modulus from dividing by b.
See BigDecimal#divmod
.
static VALUE BigDecimal_mod(VALUE self, VALUE r)
static VALUE BigDecimal_mult(VALUE self, VALUE r) { ENTER(5); Real *c, *a, *b; size_t mx; GUARD_OBJ(a, GetVpValue(self, 1)); if (RB_TYPE_P(r, T_FLOAT)) { b = GetVpValueWithPrec(r, 0, 1); } else if (RB_TYPE_P(r, T_RATIONAL)) { b = GetVpValueWithPrec(r, a->Prec*VpBaseFig(), 1); } else { b = GetVpValue(r,0); } if (!b) return DoSomeOne(self, r, '*'); SAVE(b); mx = a->Prec + b->Prec; GUARD_OBJ(c, NewZeroWrapLimited(1, mx * (VpBaseFig() + 1))); VpMult(c, a, b); return VpCheckGetValue(c); }
Returns the BigDecimal value of self
raised to power other
:
b = BigDecimal('3.14') b ** 2 # => 0.98596e1 b ** 2.0 # => 0.98596e1 b ** Rational(2, 1) # => 0.98596e1
Related: BigDecimal#power
.
static VALUE BigDecimal_power_op(VALUE self, VALUE exp) { return BigDecimal_power(1, &exp, self); }
Returns the BigDecimal sum of self
and value
:
b = BigDecimal('111111.111') # => 0.111111111e6 b + 2 # => 0.111113111e6 b + 2.0 # => 0.111113111e6 b + Rational(2, 1) # => 0.111113111e6 b + Complex(2, 0) # => (0.111113111e6+0i)
See the Note About Precision.
static VALUE BigDecimal_add(VALUE self, VALUE r) { ENTER(5); Real *c, *a, *b; size_t mx; GUARD_OBJ(a, GetVpValue(self, 1)); if (RB_TYPE_P(r, T_FLOAT)) { b = GetVpValueWithPrec(r, 0, 1); } else if (RB_TYPE_P(r, T_RATIONAL)) { b = GetVpValueWithPrec(r, a->Prec*VpBaseFig(), 1); } else { b = GetVpValue(r, 0); } if (!b) return DoSomeOne(self,r,'+'); SAVE(b); if (VpIsNaN(b)) return b->obj; if (VpIsNaN(a)) return a->obj; mx = GetAddSubPrec(a, b); if (mx == (size_t)-1L) { GUARD_OBJ(c, NewZeroWrapLimited(1, VpBaseFig() + 1)); VpAddSub(c, a, b, 1); } else { GUARD_OBJ(c, NewZeroWrapLimited(1, mx * (VpBaseFig() + 1))); if (!mx) { VpSetInf(c, VpGetSign(a)); } else { VpAddSub(c, a, b, 1); } } return VpCheckGetValue(c); }
Returns self
:
+BigDecimal(5) # => 0.5e1 +BigDecimal(-5) # => -0.5e1
static VALUE BigDecimal_uplus(VALUE self) { return self; }
Returns the BigDecimal difference of self
and value
:
b = BigDecimal('333333.333') # => 0.333333333e6 b - 2 # => 0.333331333e6 b - 2.0 # => 0.333331333e6 b - Rational(2, 1) # => 0.333331333e6 b - Complex(2, 0) # => (0.333331333e6+0i)
See the Note About Precision.
static VALUE BigDecimal_sub(VALUE self, VALUE r) { ENTER(5); Real *c, *a, *b; size_t mx; GUARD_OBJ(a, GetVpValue(self,1)); if (RB_TYPE_P(r, T_FLOAT)) { b = GetVpValueWithPrec(r, 0, 1); } else if (RB_TYPE_P(r, T_RATIONAL)) { b = GetVpValueWithPrec(r, a->Prec*VpBaseFig(), 1); } else { b = GetVpValue(r,0); } if (!b) return DoSomeOne(self,r,'-'); SAVE(b); if (VpIsNaN(b)) return b->obj; if (VpIsNaN(a)) return a->obj; mx = GetAddSubPrec(a,b); if (mx == (size_t)-1L) { GUARD_OBJ(c, NewZeroWrapLimited(1, VpBaseFig() + 1)); VpAddSub(c, a, b, -1); } else { GUARD_OBJ(c, NewZeroWrapLimited(1, mx *(VpBaseFig() + 1))); if (!mx) { VpSetInf(c,VpGetSign(a)); } else { VpAddSub(c, a, b, -1); } } return VpCheckGetValue(c); }
Returns the BigDecimal negation of self:
b0 = BigDecimal('1.5') b1 = -b0 # => -0.15e1 b2 = -b1 # => 0.15e1
static VALUE BigDecimal_neg(VALUE self) { ENTER(5); Real *c, *a; GUARD_OBJ(a, GetVpValue(self, 1)); GUARD_OBJ(c, NewZeroWrapLimited(1, a->Prec *(VpBaseFig() + 1))); VpAsgn(c, a, -1); return VpCheckGetValue(c); }
Divide by the specified value.
The result precision will be the precision of the larger operand, but its minimum is 2*Float::DIG.
See BigDecimal#div
. See BigDecimal#quo
.
static VALUE BigDecimal_div(VALUE self, VALUE r) /* For c = self/r: with round operation */ { ENTER(5); Real *c=NULL, *res=NULL, *div = NULL; r = BigDecimal_divide(self, r, &c, &res, &div); if (!NIL_P(r)) return r; /* coerced by other */ SAVE(c); SAVE(res); SAVE(div); /* a/b = c + r/b */ /* c xxxxx r 00000yyyyy ==> (y/b)*BASE >= HALF_BASE */ /* Round */ if (VpHasVal(div)) { /* frac[0] must be zero for NaN,INF,Zero */ VpInternalRound(c, 0, c->frac[c->Prec-1], (DECDIG)(VpBaseVal() * (DECDIG_DBL)res->frac[0] / div->frac[0])); } return VpCheckGetValue(c); }
Returns true
if self
is less than other
, false
otherwise:
b = BigDecimal('1.5') # => 0.15e1 b < 2 # => true b < 2.0 # => true b < Rational(2, 1) # => true b < 1.5 # => false
Raises an exception if the comparison cannot be made.
static VALUE BigDecimal_lt(VALUE self, VALUE r) { return BigDecimalCmp(self, r, '<'); }
Returns true
if self
is less or equal to than other
, false
otherwise:
b = BigDecimal('1.5') # => 0.15e1 b <= 2 # => true b <= 2.0 # => true b <= Rational(2, 1) # => true b <= 1.5 # => true b < 1 # => false
Raises an exception if the comparison cannot be made.
static VALUE BigDecimal_le(VALUE self, VALUE r) { return BigDecimalCmp(self, r, 'L'); }
The comparison operator. a <=> b is 0 if a == b, 1 if a > b, -1 if a < b.
static VALUE BigDecimal_comp(VALUE self, VALUE r) { return BigDecimalCmp(self, r, '*'); }
Tests for value equality; returns true if the values are equal.
The == and === operators and the eql? method have the same implementation for BigDecimal
.
Values may be coerced to perform the comparison:
BigDecimal('1.0') == 1.0 #=> true
static VALUE BigDecimal_eq(VALUE self, VALUE r) { return BigDecimalCmp(self, r, '='); }
Tests for value equality; returns true if the values are equal.
The == and === operators and the eql? method have the same implementation for BigDecimal
.
Values may be coerced to perform the comparison:
BigDecimal('1.0') == 1.0 #=> true
Returns true
if self
is greater than other
, false
otherwise:
b = BigDecimal('1.5') b > 1 # => true b > 1.0 # => true b > Rational(1, 1) # => true b > 2 # => false
Raises an exception if the comparison cannot be made.
static VALUE BigDecimal_gt(VALUE self, VALUE r) { return BigDecimalCmp(self, r, '>'); }
Returns true
if self
is greater than or equal to other
, false
otherwise:
b = BigDecimal('1.5') b >= 1 # => true b >= 1.0 # => true b >= Rational(1, 1) # => true b >= 1.5 # => true b > 2 # => false
Raises an exception if the comparison cannot be made.
static VALUE BigDecimal_ge(VALUE self, VALUE r) { return BigDecimalCmp(self, r, 'G'); }
Returns a string representing the marshalling of self
. See module Marshal.
inf = BigDecimal('Infinity') # => Infinity dumped = inf._dump # => "9:Infinity" BigDecimal._load(dumped) # => Infinity
static VALUE BigDecimal_dump(int argc, VALUE *argv, VALUE self) { ENTER(5); Real *vp; char *psz; VALUE dummy; volatile VALUE dump; size_t len; rb_scan_args(argc, argv, "01", &dummy); GUARD_OBJ(vp,GetVpValue(self, 1)); dump = rb_str_new(0, VpNumOfChars(vp, "E")+50); psz = RSTRING_PTR(dump); snprintf(psz, RSTRING_LEN(dump), "%"PRIuSIZE":", VpMaxPrec(vp)*VpBaseFig()); len = strlen(psz); VpToString(vp, psz+len, RSTRING_LEN(dump)-len, 0, 0); rb_str_resize(dump, strlen(psz)); return dump; }
Returns the BigDecimal absolute value of self
:
BigDecimal('5').abs # => 0.5e1 BigDecimal('-3').abs # => 0.3e1
static VALUE BigDecimal_abs(VALUE self) { ENTER(5); Real *c, *a; size_t mx; GUARD_OBJ(a, GetVpValue(self, 1)); mx = a->Prec *(VpBaseFig() + 1); GUARD_OBJ(c, NewZeroWrapLimited(1, mx)); VpAsgn(c, a, 1); VpChangeSign(c, 1); return VpCheckGetValue(c); }
Returns the BigDecimal sum of self
and value
with a precision of ndigits
decimal digits.
When ndigits
is less than the number of significant digits in the sum, the sum is rounded to that number of digits, according to the current rounding mode; see BigDecimal.mode
.
Examples:
# Set the rounding mode. BigDecimal.mode(BigDecimal::ROUND_MODE, :half_up) b = BigDecimal('111111.111') b.add(1, 0) # => 0.111112111e6 b.add(1, 3) # => 0.111e6 b.add(1, 6) # => 0.111112e6 b.add(1, 15) # => 0.111112111e6 b.add(1.0, 15) # => 0.111112111e6 b.add(Rational(1, 1), 15) # => 0.111112111e6
static VALUE BigDecimal_add2(VALUE self, VALUE b, VALUE n) { ENTER(2); Real *cv; SIGNED_VALUE mx = check_int_precision(n); if (mx == 0) return BigDecimal_add(self, b); else { size_t pl = VpSetPrecLimit(0); VALUE c = BigDecimal_add(self, b); VpSetPrecLimit(pl); GUARD_OBJ(cv, GetVpValue(c, 1)); VpLeftRound(cv, VpGetRoundMode(), mx); return VpCheckGetValue(cv); } }
Return the smallest integer greater than or equal to the value, as a BigDecimal
.
BigDecimal('3.14159').ceil #=> 4 BigDecimal('-9.1').ceil #=> -9
If n is specified and positive, the fractional part of the result has no more than that many digits.
If n is specified and negative, at least that many digits to the left of the decimal point will be 0 in the result.
BigDecimal('3.14159').ceil(3) #=> 3.142 BigDecimal('13345.234').ceil(-2) #=> 13400.0
static VALUE BigDecimal_ceil(int argc, VALUE *argv, VALUE self) { ENTER(5); Real *c, *a; int iLoc; VALUE vLoc; size_t mx, pl = VpSetPrecLimit(0); if (rb_scan_args(argc, argv, "01", &vLoc) == 0) { iLoc = 0; } else { iLoc = NUM2INT(vLoc); } GUARD_OBJ(a, GetVpValue(self, 1)); mx = a->Prec * (VpBaseFig() + 1); GUARD_OBJ(c, NewZeroWrapLimited(1, mx)); VpSetPrecLimit(pl); VpActiveRound(c, a, VP_ROUND_CEIL, iLoc); if (argc == 0) { return BigDecimal_to_i(VpCheckGetValue(c)); } return VpCheckGetValue(c); }
static VALUE BigDecimal_clone(VALUE self) { return self; }
The coerce method provides support for Ruby type coercion. It is not enabled by default.
This means that binary operations like + * / or - can often be performed on a BigDecimal
and an object of another type, if the other object can be coerced into a BigDecimal
value.
e.g.
a = BigDecimal("1.0") b = a / 2.0 #=> 0.5
Note that coercing a String
to a BigDecimal
is not supported by default; it requires a special compile-time option when building Ruby.
static VALUE BigDecimal_coerce(VALUE self, VALUE other) { ENTER(2); VALUE obj; Real *b; if (RB_TYPE_P(other, T_FLOAT)) { GUARD_OBJ(b, GetVpValueWithPrec(other, 0, 1)); obj = rb_assoc_new(VpCheckGetValue(b), self); } else { if (RB_TYPE_P(other, T_RATIONAL)) { Real* pv = DATA_PTR(self); GUARD_OBJ(b, GetVpValueWithPrec(other, pv->Prec*VpBaseFig(), 1)); } else { GUARD_OBJ(b, GetVpValue(other, 1)); } obj = rb_assoc_new(b->obj, self); } return obj; }
Divide by the specified value.
- digits
-
If specified and less than the number of significant digits of the result, the result is rounded to that number of digits, according to
BigDecimal.mode
.If digits is 0, the result is the same as for the / operator or
quo
.If digits is not specified, the result is an integer, by analogy with Float#div; see also
BigDecimal#divmod
.
See BigDecimal#/. See BigDecimal#quo
.
Examples:
a = BigDecimal("4") b = BigDecimal("3") a.div(b, 3) # => 0.133e1 a.div(b, 0) # => 0.1333333333333333333e1 a / b # => 0.1333333333333333333e1 a.quo(b) # => 0.1333333333333333333e1 a.div(b) # => 1
static VALUE BigDecimal_div3(int argc, VALUE *argv, VALUE self) { VALUE b,n; rb_scan_args(argc, argv, "11", &b, &n); return BigDecimal_div2(self, b, n); }
Divides by the specified value, and returns the quotient and modulus as BigDecimal
numbers. The quotient is rounded towards negative infinity.
For example:
require 'bigdecimal' a = BigDecimal("42") b = BigDecimal("9") q, m = a.divmod(b) c = q * b + m a == c #=> true
The quotient q is (a/b).floor, and the modulus is the amount that must be added to q * b to get a.
static VALUE BigDecimal_divmod(VALUE self, VALUE r) { ENTER(5); Real *div = NULL, *mod = NULL; if (BigDecimal_DoDivmod(self, r, &div, &mod)) { SAVE(div); SAVE(mod); return rb_assoc_new(VpCheckGetValue(div), VpCheckGetValue(mod)); } return DoSomeOne(self,r,rb_intern("divmod")); }
Tests for value equality; returns true if the values are equal.
The == and === operators and the eql? method have the same implementation for BigDecimal
.
Values may be coerced to perform the comparison:
BigDecimal('1.0') == 1.0 #=> true
Returns the exponent of the BigDecimal
number, as an Integer
.
If the number can be represented as 0.xxxxxx*10**n where xxxxxx is a string of digits with no leading zeros, then n is the exponent.
static VALUE BigDecimal_exponent(VALUE self) { ssize_t e = VpExponent10(GetVpValue(self, 1)); return SSIZET2NUM(e); }
Returns True if the value is finite (not NaN or infinite).
static VALUE BigDecimal_IsFinite(VALUE self) { Real *p = GetVpValue(self, 1); if (VpIsNaN(p)) return Qfalse; if (VpIsInf(p)) return Qfalse; return Qtrue; }
Return the integer part of the number, as a BigDecimal
.
static VALUE BigDecimal_fix(VALUE self) { ENTER(5); Real *c, *a; size_t mx; GUARD_OBJ(a, GetVpValue(self, 1)); mx = a->Prec *(VpBaseFig() + 1); GUARD_OBJ(c, NewZeroWrapLimited(1, mx)); VpActiveRound(c, a, VP_ROUND_DOWN, 0); /* 0: round off */ return VpCheckGetValue(c); }
Return the largest integer less than or equal to the value, as a BigDecimal
.
BigDecimal('3.14159').floor #=> 3 BigDecimal('-9.1').floor #=> -10
If n is specified and positive, the fractional part of the result has no more than that many digits.
If n is specified and negative, at least that many digits to the left of the decimal point will be 0 in the result.
BigDecimal('3.14159').floor(3) #=> 3.141 BigDecimal('13345.234').floor(-2) #=> 13300.0
static VALUE BigDecimal_floor(int argc, VALUE *argv, VALUE self) { ENTER(5); Real *c, *a; int iLoc; VALUE vLoc; size_t mx, pl = VpSetPrecLimit(0); if (rb_scan_args(argc, argv, "01", &vLoc)==0) { iLoc = 0; } else { iLoc = NUM2INT(vLoc); } GUARD_OBJ(a, GetVpValue(self, 1)); mx = a->Prec * (VpBaseFig() + 1); GUARD_OBJ(c, NewZeroWrapLimited(1, mx)); VpSetPrecLimit(pl); VpActiveRound(c, a, VP_ROUND_FLOOR, iLoc); #ifdef BIGDECIMAL_DEBUG VPrint(stderr, "floor: c=%\n", c); #endif if (argc == 0) { return BigDecimal_to_i(VpCheckGetValue(c)); } return VpCheckGetValue(c); }
Return the fractional part of the number, as a BigDecimal
.
static VALUE BigDecimal_frac(VALUE self) { ENTER(5); Real *c, *a; size_t mx; GUARD_OBJ(a, GetVpValue(self, 1)); mx = a->Prec * (VpBaseFig() + 1); GUARD_OBJ(c, NewZeroWrapLimited(1, mx)); VpFrac(c, a); return VpCheckGetValue(c); }
Returns the integer hash value for self
.
Two instances of BigDecimal have the same hash value if and only if they have equal:
-
Sign.
-
Fractional part.
-
Exponent.
static VALUE BigDecimal_hash(VALUE self) { ENTER(1); Real *p; st_index_t hash; GUARD_OBJ(p, GetVpValue(self, 1)); hash = (st_index_t)p->sign; /* hash!=2: the case for 0(1),NaN(0) or +-Infinity(3) is sign itself */ if(hash == 2 || hash == (st_index_t)-2) { hash ^= rb_memhash(p->frac, sizeof(DECDIG)*p->Prec); hash += p->exponent; } return ST2FIX(hash); }
Returns nil, -1, or +1 depending on whether the value is finite, -Infinity, or +Infinity.
static VALUE BigDecimal_IsInfinite(VALUE self) { Real *p = GetVpValue(self, 1); if (VpIsPosInf(p)) return INT2FIX(1); if (VpIsNegInf(p)) return INT2FIX(-1); return Qnil; }
Returns a string representation of self.
BigDecimal("1234.5678").inspect #=> "0.12345678e4"
static VALUE BigDecimal_inspect(VALUE self) { ENTER(5); Real *vp; volatile VALUE str; size_t nc; GUARD_OBJ(vp, GetVpValue(self, 1)); nc = VpNumOfChars(vp, "E"); str = rb_str_new(0, nc); VpToString(vp, RSTRING_PTR(str), RSTRING_LEN(str), 0, 0); rb_str_resize(str, strlen(RSTRING_PTR(str))); return str; }
Returns the BigDecimal product of self
and value
with a precision of ndigits
decimal digits.
When ndigits
is less than the number of significant digits in the sum, the sum is rounded to that number of digits, according to the current rounding mode; see BigDecimal.mode
.
Examples:
# Set the rounding mode. BigDecimal.mode(BigDecimal::ROUND_MODE, :half_up) b = BigDecimal('555555.555') b.mult(3, 0) # => 0.1666666665e7 b.mult(3, 3) # => 0.167e7 b.mult(3, 6) # => 0.166667e7 b.mult(3, 15) # => 0.1666666665e7 b.mult(3.0, 0) # => 0.1666666665e7 b.mult(Rational(3, 1), 0) # => 0.1666666665e7 b.mult(Complex(3, 0), 0) # => (0.1666666665e7+0.0i)
static VALUE BigDecimal_mult2(VALUE self, VALUE b, VALUE n) { ENTER(2); Real *cv; SIGNED_VALUE mx = check_int_precision(n); if (mx == 0) return BigDecimal_mult(self, b); else { size_t pl = VpSetPrecLimit(0); VALUE c = BigDecimal_mult(self, b); VpSetPrecLimit(pl); GUARD_OBJ(cv, GetVpValue(c, 1)); VpLeftRound(cv, VpGetRoundMode(), mx); return VpCheckGetValue(cv); } }
Returns the number of decimal significant digits in self
.
BigDecimal("0").n_significant_digits # => 0 BigDecimal("1").n_significant_digits # => 1 BigDecimal("1.1").n_significant_digits # => 2 BigDecimal("3.1415").n_significant_digits # => 5 BigDecimal("-1e20").n_significant_digits # => 1 BigDecimal("1e-20").n_significant_digits # => 1 BigDecimal("Infinity").n_significant_digits # => 0 BigDecimal("-Infinity").n_significant_digits # => 0 BigDecimal("NaN").n_significant_digits # => 0
static VALUE BigDecimal_n_significant_digits(VALUE self) { ENTER(1); Real *p; GUARD_OBJ(p, GetVpValue(self, 1)); if (VpIsZero(p) || !VpIsDef(p)) { return INT2FIX(0); } ssize_t n = p->Prec; /* The length of frac without trailing zeros. */ for (n = p->Prec; n > 0 && p->frac[n-1] == 0; --n); if (n == 0) return INT2FIX(0); DECDIG x; int nlz = BASE_FIG; for (x = p->frac[0]; x > 0; x /= 10) --nlz; int ntz = 0; for (x = p->frac[n-1]; x > 0 && x % 10 == 0; x /= 10) ++ntz; ssize_t n_significant_digits = BASE_FIG*n - nlz - ntz; return SSIZET2NUM(n_significant_digits); }
Returns True if the value is Not a Number.
static VALUE BigDecimal_IsNaN(VALUE self) { Real *p = GetVpValue(self, 1); if (VpIsNaN(p)) return Qtrue; return Qfalse; }
Returns self if the value is non-zero, nil otherwise.
static VALUE BigDecimal_nonzero(VALUE self) { Real *a = GetVpValue(self, 1); return VpIsZero(a) ? Qnil : self; }
Returns the value raised to the power of n.
Note that n must be an Integer
.
Also available as the operator **.
static VALUE BigDecimal_power(int argc, VALUE*argv, VALUE self) { ENTER(5); VALUE vexp, prec; Real* exp = NULL; Real *x, *y; ssize_t mp, ma, n; SIGNED_VALUE int_exp; double d; rb_scan_args(argc, argv, "11", &vexp, &prec); GUARD_OBJ(x, GetVpValue(self, 1)); n = NIL_P(prec) ? (ssize_t)(x->Prec*VpBaseFig()) : NUM2SSIZET(prec); if (VpIsNaN(x)) { y = NewZeroWrapLimited(1, n); VpSetNaN(y); RB_GC_GUARD(y->obj); return VpCheckGetValue(y); } retry: switch (TYPE(vexp)) { case T_FIXNUM: break; case T_BIGNUM: break; case T_FLOAT: d = RFLOAT_VALUE(vexp); if (d == round(d)) { if (FIXABLE(d)) { vexp = LONG2FIX((long)d); } else { vexp = rb_dbl2big(d); } goto retry; } if (NIL_P(prec)) { n += BIGDECIMAL_DOUBLE_FIGURES; } exp = GetVpValueWithPrec(vexp, 0, 1); break; case T_RATIONAL: if (is_zero(rb_rational_num(vexp))) { if (is_positive(vexp)) { vexp = INT2FIX(0); goto retry; } } else if (is_one(rb_rational_den(vexp))) { vexp = rb_rational_num(vexp); goto retry; } exp = GetVpValueWithPrec(vexp, n, 1); if (NIL_P(prec)) { n += n; } break; case T_DATA: if (is_kind_of_BigDecimal(vexp)) { VALUE zero = INT2FIX(0); VALUE rounded = BigDecimal_round(1, &zero, vexp); if (RTEST(BigDecimal_eq(vexp, rounded))) { vexp = BigDecimal_to_i(vexp); goto retry; } if (NIL_P(prec)) { GUARD_OBJ(y, GetVpValue(vexp, 1)); n += y->Prec*VpBaseFig(); } exp = DATA_PTR(vexp); break; } /* fall through */ default: rb_raise(rb_eTypeError, "wrong argument type %"PRIsVALUE" (expected scalar Numeric)", RB_OBJ_CLASSNAME(vexp)); } if (VpIsZero(x)) { if (is_negative(vexp)) { y = NewZeroWrapNolimit(1, n); if (BIGDECIMAL_NEGATIVE_P(x)) { if (is_integer(vexp)) { if (is_even(vexp)) { /* (-0) ** (-even_integer) -> Infinity */ VpSetPosInf(y); } else { /* (-0) ** (-odd_integer) -> -Infinity */ VpSetNegInf(y); } } else { /* (-0) ** (-non_integer) -> Infinity */ VpSetPosInf(y); } } else { /* (+0) ** (-num) -> Infinity */ VpSetPosInf(y); } RB_GC_GUARD(y->obj); return VpCheckGetValue(y); } else if (is_zero(vexp)) { return VpCheckGetValue(NewOneWrapLimited(1, n)); } else { return VpCheckGetValue(NewZeroWrapLimited(1, n)); } } if (is_zero(vexp)) { return VpCheckGetValue(NewOneWrapLimited(1, n)); } else if (is_one(vexp)) { return self; } if (VpIsInf(x)) { if (is_negative(vexp)) { if (BIGDECIMAL_NEGATIVE_P(x)) { if (is_integer(vexp)) { if (is_even(vexp)) { /* (-Infinity) ** (-even_integer) -> +0 */ return VpCheckGetValue(NewZeroWrapLimited(1, n)); } else { /* (-Infinity) ** (-odd_integer) -> -0 */ return VpCheckGetValue(NewZeroWrapLimited(-1, n)); } } else { /* (-Infinity) ** (-non_integer) -> -0 */ return VpCheckGetValue(NewZeroWrapLimited(-1, n)); } } else { return VpCheckGetValue(NewZeroWrapLimited(1, n)); } } else { y = NewZeroWrapLimited(1, n); if (BIGDECIMAL_NEGATIVE_P(x)) { if (is_integer(vexp)) { if (is_even(vexp)) { VpSetPosInf(y); } else { VpSetNegInf(y); } } else { /* TODO: support complex */ rb_raise(rb_eMathDomainError, "a non-integral exponent for a negative base"); } } else { VpSetPosInf(y); } return VpCheckGetValue(y); } } if (exp != NULL) { return bigdecimal_power_by_bigdecimal(x, exp, n); } else if (RB_TYPE_P(vexp, T_BIGNUM)) { VALUE abs_value = BigDecimal_abs(self); if (is_one(abs_value)) { return VpCheckGetValue(NewOneWrapLimited(1, n)); } else if (RTEST(rb_funcall(abs_value, '<', 1, INT2FIX(1)))) { if (is_negative(vexp)) { y = NewZeroWrapLimited(1, n); VpSetInf(y, (is_even(vexp) ? 1 : -1) * VpGetSign(x)); return VpCheckGetValue(y); } else if (BIGDECIMAL_NEGATIVE_P(x) && is_even(vexp)) { return VpCheckGetValue(NewZeroWrapLimited(-1, n)); } else { return VpCheckGetValue(NewZeroWrapLimited(1, n)); } } else { if (is_positive(vexp)) { y = NewZeroWrapLimited(1, n); VpSetInf(y, (is_even(vexp) ? 1 : -1) * VpGetSign(x)); return VpCheckGetValue(y); } else if (BIGDECIMAL_NEGATIVE_P(x) && is_even(vexp)) { return VpCheckGetValue(NewZeroWrapLimited(-1, n)); } else { return VpCheckGetValue(NewZeroWrapLimited(1, n)); } } } int_exp = FIX2LONG(vexp); ma = int_exp; if (ma < 0) ma = -ma; if (ma == 0) ma = 1; if (VpIsDef(x)) { mp = x->Prec * (VpBaseFig() + 1); GUARD_OBJ(y, NewZeroWrapLimited(1, mp * (ma + 1))); } else { GUARD_OBJ(y, NewZeroWrapLimited(1, 1)); } VpPowerByInt(y, x, int_exp); if (!NIL_P(prec) && VpIsDef(y)) { VpMidRound(y, VpGetRoundMode(), n); } return VpCheckGetValue(y); }
Returns the number of decimal digits in self
:
BigDecimal("0").precision # => 0 BigDecimal("1").precision # => 1 BigDecimal("1.1").precision # => 2 BigDecimal("3.1415").precision # => 5 BigDecimal("-1e20").precision # => 21 BigDecimal("1e-20").precision # => 20 BigDecimal("Infinity").precision # => 0 BigDecimal("-Infinity").precision # => 0 BigDecimal("NaN").precision # => 0
static VALUE BigDecimal_precision(VALUE self) { ssize_t precision; BigDecimal_count_precision_and_scale(self, &precision, NULL); return SSIZET2NUM(precision); }
Returns a 2-length array; the first item is the result of BigDecimal#precision
and the second one is of BigDecimal#scale
.
See BigDecimal#precision
. See BigDecimal#scale
.
static VALUE BigDecimal_precision_scale(VALUE self) { ssize_t precision, scale; BigDecimal_count_precision_and_scale(self, &precision, &scale); return rb_assoc_new(SSIZET2NUM(precision), SSIZET2NUM(scale)); }
Returns an Array of two Integer
values that represent platform-dependent internal storage properties.
This method is deprecated and will be removed in the future. Instead, use BigDecimal#n_significant_digits
for obtaining the number of significant digits in scientific notation, and BigDecimal#precision
for obtaining the number of digits in decimal notation.
static VALUE BigDecimal_prec(VALUE self) { ENTER(1); Real *p; VALUE obj; rb_category_warn(RB_WARN_CATEGORY_DEPRECATED, "BigDecimal#precs is deprecated and will be removed in the future; " "use BigDecimal#precision instead."); GUARD_OBJ(p, GetVpValue(self, 1)); obj = rb_assoc_new(SIZET2NUM(p->Prec*VpBaseFig()), SIZET2NUM(p->MaxPrec*VpBaseFig())); return obj; }
Divide by the specified value.
- digits
-
If specified and less than the number of significant digits of the result, the result is rounded to the given number of digits, according to the rounding mode indicated by
BigDecimal.mode
.If digits is 0 or omitted, the result is the same as for the / operator.
See BigDecimal#/. See BigDecimal#div
.
static VALUE BigDecimal_quo(int argc, VALUE *argv, VALUE self) { VALUE value, digits, result; SIGNED_VALUE n = -1; argc = rb_scan_args(argc, argv, "11", &value, &digits); if (argc > 1) { n = check_int_precision(digits); } if (n > 0) { result = BigDecimal_div2(self, value, digits); } else { result = BigDecimal_div(self, value); } return result; }
Returns the remainder from dividing by the value.
x.remainder(y) means x-y*(x/y).truncate
static VALUE BigDecimal_remainder(VALUE self, VALUE r) /* remainder */ { VALUE f; Real *d, *rv = 0; f = BigDecimal_divremain(self, r, &d, &rv); if (!NIL_P(f)) return f; return VpCheckGetValue(rv); }
Round to the nearest integer (by default), returning the result as a BigDecimal
if n is specified, or as an Integer
if it isn’t.
BigDecimal('3.14159').round #=> 3 BigDecimal('8.7').round #=> 9 BigDecimal('-9.9').round #=> -10 BigDecimal('3.14159').round(2).class.name #=> "BigDecimal" BigDecimal('3.14159').round.class.name #=> "Integer"
If n is specified and positive, the fractional part of the result has no more than that many digits.
If n is specified and negative, at least that many digits to the left of the decimal point will be 0 in the result, and return value will be an Integer
.
BigDecimal('3.14159').round(3) #=> 3.142 BigDecimal('13345.234').round(-2) #=> 13300
The value of the optional mode argument can be used to determine how rounding is performed; see BigDecimal.mode
.
static VALUE BigDecimal_round(int argc, VALUE *argv, VALUE self) { ENTER(5); Real *c, *a; int iLoc = 0; VALUE vLoc; VALUE vRound; int round_to_int = 0; size_t mx, pl; unsigned short sw = VpGetRoundMode(); switch (rb_scan_args(argc, argv, "02", &vLoc, &vRound)) { case 0: iLoc = 0; round_to_int = 1; break; case 1: if (RB_TYPE_P(vLoc, T_HASH)) { sw = check_rounding_mode_option(vLoc); } else { iLoc = NUM2INT(vLoc); if (iLoc < 1) round_to_int = 1; } break; case 2: iLoc = NUM2INT(vLoc); if (RB_TYPE_P(vRound, T_HASH)) { sw = check_rounding_mode_option(vRound); } else { sw = check_rounding_mode(vRound); } break; default: break; } pl = VpSetPrecLimit(0); GUARD_OBJ(a, GetVpValue(self, 1)); mx = a->Prec * (VpBaseFig() + 1); GUARD_OBJ(c, NewZeroWrapLimited(1, mx)); VpSetPrecLimit(pl); VpActiveRound(c, a, sw, iLoc); if (round_to_int) { return BigDecimal_to_i(VpCheckGetValue(c)); } return VpCheckGetValue(c); }
Returns the number of decimal digits following the decimal digits in self
.
BigDecimal("0").scale # => 0 BigDecimal("1").scale # => 0 BigDecimal("1.1").scale # => 1 BigDecimal("3.1415").scale # => 4 BigDecimal("-1e20").precision # => 0 BigDecimal("1e-20").precision # => 20 BigDecimal("Infinity").scale # => 0 BigDecimal("-Infinity").scale # => 0 BigDecimal("NaN").scale # => 0
static VALUE BigDecimal_scale(VALUE self) { ssize_t scale; BigDecimal_count_precision_and_scale(self, NULL, &scale); return SSIZET2NUM(scale); }
Returns the sign of the value.
Returns a positive value if > 0, a negative value if < 0. It behaves the same with zeros - it returns a positive value for a positive zero (BigDecimal(‘0’)) and a negative value for a negative zero (BigDecimal(‘-0’)).
The specific value returned indicates the type and sign of the BigDecimal
, as follows:
BigDecimal::SIGN_NaN
-
value is Not a Number
BigDecimal::SIGN_POSITIVE_ZERO
-
value is +0
BigDecimal::SIGN_NEGATIVE_ZERO
-
value is -0
BigDecimal::SIGN_POSITIVE_INFINITE
-
value is +Infinity
BigDecimal::SIGN_NEGATIVE_INFINITE
-
value is -Infinity
BigDecimal::SIGN_POSITIVE_FINITE
-
value is positive
BigDecimal::SIGN_NEGATIVE_FINITE
-
value is negative
static VALUE BigDecimal_sign(VALUE self) { /* sign */ int s = GetVpValue(self, 1)->sign; return INT2FIX(s); }
Splits a BigDecimal
number into four parts, returned as an array of values.
The first value represents the sign of the BigDecimal
, and is -1 or 1, or 0 if the BigDecimal
is Not a Number.
The second value is a string representing the significant digits of the BigDecimal
, with no leading zeros.
The third value is the base used for arithmetic (currently always 10) as an Integer
.
The fourth value is an Integer
exponent.
If the BigDecimal
can be represented as 0.xxxxxx*10**n, then xxxxxx is the string of significant digits with no leading zeros, and n is the exponent.
From these values, you can translate a BigDecimal
to a float as follows:
sign, significant_digits, base, exponent = a.split f = sign * "0.#{significant_digits}".to_f * (base ** exponent)
(Note that the to_f
method is provided as a more convenient way to translate a BigDecimal
to a Float
.)
static VALUE BigDecimal_split(VALUE self) { ENTER(5); Real *vp; VALUE obj,str; ssize_t e, s; char *psz1; GUARD_OBJ(vp, GetVpValue(self, 1)); str = rb_str_new(0, VpNumOfChars(vp, "E")); psz1 = RSTRING_PTR(str); VpSzMantissa(vp, psz1, RSTRING_LEN(str)); s = 1; if(psz1[0] == '-') { size_t len = strlen(psz1 + 1); memmove(psz1, psz1 + 1, len); psz1[len] = '\0'; s = -1; } if (psz1[0] == 'N') s = 0; /* NaN */ e = VpExponent10(vp); obj = rb_ary_new2(4); rb_ary_push(obj, INT2FIX(s)); rb_ary_push(obj, str); rb_str_resize(str, strlen(psz1)); rb_ary_push(obj, INT2FIX(10)); rb_ary_push(obj, SSIZET2NUM(e)); return obj; }
Returns the square root of the value.
Result has at least n significant digits.
static VALUE BigDecimal_sqrt(VALUE self, VALUE nFig) { ENTER(5); Real *c, *a; size_t mx, n; GUARD_OBJ(a, GetVpValue(self, 1)); mx = a->Prec * (VpBaseFig() + 1); n = check_int_precision(nFig); n += VpDblFig() + VpBaseFig(); if (mx <= n) mx = n; GUARD_OBJ(c, NewZeroWrapLimited(1, mx)); VpSqrt(c, a); return VpCheckGetValue(c); }
Subtract the specified value.
e.g.
c = a.sub(b,n)
- digits
-
If specified and less than the number of significant digits of the result, the result is rounded to that number of digits, according to
BigDecimal.mode
.
static VALUE BigDecimal_sub2(VALUE self, VALUE b, VALUE n) { ENTER(2); Real *cv; SIGNED_VALUE mx = check_int_precision(n); if (mx == 0) return BigDecimal_sub(self, b); else { size_t pl = VpSetPrecLimit(0); VALUE c = BigDecimal_sub(self, b); VpSetPrecLimit(pl); GUARD_OBJ(cv, GetVpValue(c, 1)); VpLeftRound(cv, VpGetRoundMode(), mx); return VpCheckGetValue(cv); } }
Returns self.
require 'bigdecimal/util' d = BigDecimal("3.14") d.to_d # => 0.314e1
# File bigdecimal/lib/bigdecimal/util.rb, line 110 def to_d self end
Converts a BigDecimal
to a String
of the form “nnnnnn.mmm”. This method is deprecated; use BigDecimal#to_s
(“F”) instead.
require 'bigdecimal/util' d = BigDecimal("3.14") d.to_digits # => "3.14"
# File bigdecimal/lib/bigdecimal/util.rb, line 90 def to_digits if self.nan? || self.infinite? || self.zero? self.to_s else i = self.to_i.to_s _,f,_,z = self.frac.split i + "." + ("0"*(-z)) + f end end
Returns a new Float
object having approximately the same value as the BigDecimal
number. Normal accuracy limits and built-in errors of binary Float
arithmetic apply.
static VALUE BigDecimal_to_f(VALUE self) { ENTER(1); Real *p; double d; SIGNED_VALUE e; char *buf; volatile VALUE str; GUARD_OBJ(p, GetVpValue(self, 1)); if (VpVtoD(&d, &e, p) != 1) return rb_float_new(d); if (e > (SIGNED_VALUE)(DBL_MAX_10_EXP+BASE_FIG)) goto overflow; if (e < (SIGNED_VALUE)(DBL_MIN_10_EXP-BASE_FIG)) goto underflow; str = rb_str_new(0, VpNumOfChars(p, "E")); buf = RSTRING_PTR(str); VpToString(p, buf, RSTRING_LEN(str), 0, 0); errno = 0; d = strtod(buf, 0); if (errno == ERANGE) { if (d == 0.0) goto underflow; if (fabs(d) >= HUGE_VAL) goto overflow; } return rb_float_new(d); overflow: VpException(VP_EXCEPTION_OVERFLOW, "BigDecimal to Float conversion", 0); if (BIGDECIMAL_NEGATIVE_P(p)) return rb_float_new(VpGetDoubleNegInf()); else return rb_float_new(VpGetDoublePosInf()); underflow: VpException(VP_EXCEPTION_UNDERFLOW, "BigDecimal to Float conversion", 0); if (BIGDECIMAL_NEGATIVE_P(p)) return rb_float_new(-0.0); else return rb_float_new(0.0); }
Returns the value as an Integer
.
If the BigDecimal
is infinity or NaN, raises FloatDomainError.
static VALUE BigDecimal_to_i(VALUE self) { ENTER(5); ssize_t e, nf; Real *p; GUARD_OBJ(p, GetVpValue(self, 1)); BigDecimal_check_num(p); e = VpExponent10(p); if (e <= 0) return INT2FIX(0); nf = VpBaseFig(); if (e <= nf) { return LONG2NUM((long)(VpGetSign(p) * (DECDIG_DBL_SIGNED)p->frac[0])); } else { VALUE a = BigDecimal_split(self); VALUE digits = RARRAY_AREF(a, 1); VALUE numerator = rb_funcall(digits, rb_intern("to_i"), 0); VALUE ret; ssize_t dpower = e - (ssize_t)RSTRING_LEN(digits); if (BIGDECIMAL_NEGATIVE_P(p)) { numerator = rb_funcall(numerator, '*', 1, INT2FIX(-1)); } if (dpower < 0) { ret = rb_funcall(numerator, rb_intern("div"), 1, rb_funcall(INT2FIX(10), rb_intern("**"), 1, INT2FIX(-dpower))); } else { ret = rb_funcall(numerator, '*', 1, rb_funcall(INT2FIX(10), rb_intern("**"), 1, INT2FIX(dpower))); } if (RB_TYPE_P(ret, T_FLOAT)) { rb_raise(rb_eFloatDomainError, "Infinity"); } return ret; } }
Returns the value as an Integer
.
If the BigDecimal
is infinity or NaN, raises FloatDomainError.
Converts a BigDecimal
to a Rational
.
static VALUE BigDecimal_to_r(VALUE self) { Real *p; ssize_t sign, power, denomi_power; VALUE a, digits, numerator; p = GetVpValue(self, 1); BigDecimal_check_num(p); sign = VpGetSign(p); power = VpExponent10(p); a = BigDecimal_split(self); digits = RARRAY_AREF(a, 1); denomi_power = power - RSTRING_LEN(digits); numerator = rb_funcall(digits, rb_intern("to_i"), 0); if (sign < 0) { numerator = rb_funcall(numerator, '*', 1, INT2FIX(-1)); } if (denomi_power < 0) { return rb_Rational(numerator, rb_funcall(INT2FIX(10), rb_intern("**"), 1, INT2FIX(-denomi_power))); } else { return rb_Rational1(rb_funcall(numerator, '*', 1, rb_funcall(INT2FIX(10), rb_intern("**"), 1, INT2FIX(denomi_power)))); } }
Converts the value to a string.
The default format looks like 0.xxxxEnn.
The optional parameter s consists of either an integer; or an optional ‘+’ or ‘ ’, followed by an optional number, followed by an optional ‘E’ or ‘F’.
If there is a ‘+’ at the start of s, positive values are returned with a leading ‘+’.
A space at the start of s returns positive values with a leading space.
If s contains a number, a space is inserted after each group of that many digits, starting from ‘.’ and counting outwards.
If s ends with an ‘E’, engineering notation (0.xxxxEnn) is used.
If s ends with an ‘F’, conventional floating point notation is used.
Examples:
BigDecimal('-1234567890123.45678901234567890').to_s('5F') #=> '-123 45678 90123.45678 90123 45678 9' BigDecimal('1234567890123.45678901234567890').to_s('+8F') #=> '+12345 67890123.45678901 23456789' BigDecimal('1234567890123.45678901234567890').to_s(' F') #=> ' 1234567890123.4567890123456789'
static VALUE BigDecimal_to_s(int argc, VALUE *argv, VALUE self) { ENTER(5); int fmt = 0; /* 0: E format, 1: F format */ int fPlus = 0; /* 0: default, 1: set ' ' before digits, 2: set '+' before digits. */ Real *vp; volatile VALUE str; char *psz; char ch; size_t nc, mc = 0; SIGNED_VALUE m; VALUE f; GUARD_OBJ(vp, GetVpValue(self, 1)); if (rb_scan_args(argc, argv, "01", &f) == 1) { if (RB_TYPE_P(f, T_STRING)) { psz = StringValueCStr(f); if (*psz == ' ') { fPlus = 1; psz++; } else if (*psz == '+') { fPlus = 2; psz++; } while ((ch = *psz++) != 0) { if (ISSPACE(ch)) { continue; } if (!ISDIGIT(ch)) { if (ch == 'F' || ch == 'f') { fmt = 1; /* F format */ } break; } mc = mc*10 + ch - '0'; } } else { m = NUM2INT(f); if (m <= 0) { rb_raise(rb_eArgError, "argument must be positive"); } mc = (size_t)m; } } if (fmt) { nc = VpNumOfChars(vp, "F"); } else { nc = VpNumOfChars(vp, "E"); } if (mc > 0) { nc += (nc + mc - 1) / mc + 1; } str = rb_usascii_str_new(0, nc); psz = RSTRING_PTR(str); if (fmt) { VpToFString(vp, psz, RSTRING_LEN(str), mc, fPlus); } else { VpToString (vp, psz, RSTRING_LEN(str), mc, fPlus); } rb_str_resize(str, strlen(psz)); return str; }
Truncate to the nearest integer (by default), returning the result as a BigDecimal
.
BigDecimal('3.14159').truncate #=> 3 BigDecimal('8.7').truncate #=> 8 BigDecimal('-9.9').truncate #=> -9
If n is specified and positive, the fractional part of the result has no more than that many digits.
If n is specified and negative, at least that many digits to the left of the decimal point will be 0 in the result.
BigDecimal('3.14159').truncate(3) #=> 3.141 BigDecimal('13345.234').truncate(-2) #=> 13300.0
static VALUE BigDecimal_truncate(int argc, VALUE *argv, VALUE self) { ENTER(5); Real *c, *a; int iLoc; VALUE vLoc; size_t mx, pl = VpSetPrecLimit(0); if (rb_scan_args(argc, argv, "01", &vLoc) == 0) { iLoc = 0; } else { iLoc = NUM2INT(vLoc); } GUARD_OBJ(a, GetVpValue(self, 1)); mx = a->Prec * (VpBaseFig() + 1); GUARD_OBJ(c, NewZeroWrapLimited(1, mx)); VpSetPrecLimit(pl); VpActiveRound(c, a, VP_ROUND_DOWN, iLoc); /* 0: truncate */ if (argc == 0) { return BigDecimal_to_i(VpCheckGetValue(c)); } return VpCheckGetValue(c); }
Returns True if the value is zero.
static VALUE BigDecimal_zero(VALUE self) { Real *a = GetVpValue(self, 1); return VpIsZero(a) ? Qtrue : Qfalse; }