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
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
License¶ ↑
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,
BASEis 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
Positive infinity value.
- NAN
‘Not a Number’ value.
- 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));
m /= VpBaseFig();
if (m && pv->MaxPrec > m) {
pv->MaxPrec = m+1;
}
return ToValue(pv);
}
The BigDecimal.double_fig class method returns the number of digits a Float number is allowed to have. The result depends upon the CPU and OS in use.
static VALUE
BigDecimal_double_fig(VALUE self)
{
return INT2FIX(VpDblFig());
}
static VALUE
BigDecimal_s_interpret_loosely(VALUE klass, VALUE str)
{
ENTER(1);
char const *c_str;
Real *pv;
c_str = StringValueCStr(str);
GUARD_OBJ(pv, VpAlloc(0, c_str, 0, 1));
pv->obj = TypedData_Wrap_Struct(klass, &BigDecimal_data_type, pv);
RB_OBJ_FREEZE(pv->obj);
return pv->obj;
}
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;
}
Controls handling of arithmetic exceptions and rounding. If no value is supplied, the current value is returned.
Six values of the mode parameter control the handling of arithmetic exceptions:
BigDecimal::EXCEPTION_NaN BigDecimal::EXCEPTION_INFINITY BigDecimal::EXCEPTION_UNDERFLOW BigDecimal::EXCEPTION_OVERFLOW BigDecimal::EXCEPTION_ZERODIVIDE BigDecimal::EXCEPTION_ALL
For each mode parameter above, if the value set is false, computation continues after an arithmetic exception of the appropriate type. When computation continues, results are as follows:
EXCEPTION_NaN-
NaN
EXCEPTION_INFINITY-
+Infinity or -Infinity
EXCEPTION_UNDERFLOW-
0
EXCEPTION_OVERFLOW-
+Infinity or -Infinity
EXCEPTION_ZERODIVIDE-
+Infinity or -Infinity
One value of the mode parameter controls the rounding of numeric values: BigDecimal::ROUND_MODE. The values it can take are:
ROUND_UP, :up-
round away from zero
ROUND_DOWN, :down, :truncate-
round towards zero (truncate)
ROUND_HALF_UP, :half_up, :default-
round towards the nearest neighbor, unless both neighbors are equidistant, in which case round away from zero. (default)
ROUND_HALF_DOWN, :half_down-
round towards the nearest neighbor, unless both neighbors are equidistant, in which case round towards zero.
ROUND_HALF_EVEN, :half_even, :banker-
round towards the nearest neighbor, unless both neighbors are equidistant, in which case round towards the even neighbor (Banker’s rounding)
ROUND_CEILING, :ceiling, :ceil-
round towards positive infinity (ceil)
ROUND_FLOOR, :floor-
round towards negative infinity (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)
Multiply by the specified value.
e.g.
c = a.mult(b,n) c = a * b
- 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_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, DBLE_FIG, 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, VpCreateRbObject(mx *(VpBaseFig() + 1), "0"));
VpMult(c, a, b);
return ToValue(c);
}
Returns the value raised to the power of n.
See BigDecimal#power.
static VALUE
BigDecimal_power_op(VALUE self, VALUE exp)
{
return BigDecimal_power(1, &exp, self);
}
Add the specified value.
e.g.
c = a.add(b,n) c = a + b
- 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_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, DBLE_FIG, 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,VpCreateRbObject(VpBaseFig() + 1, "0"));
VpAddSub(c, a, b, 1);
}
else {
GUARD_OBJ(c, VpCreateRbObject(mx * (VpBaseFig() + 1), "0"));
if(!mx) {
VpSetInf(c, VpGetSign(a));
}
else {
VpAddSub(c, a, b, 1);
}
}
return ToValue(c);
}
Return self.
+BigDecimal('5') #=> 0.5e1
static VALUE
BigDecimal_uplus(VALUE self)
{
return self;
}
Subtract the specified value.
e.g.
c = a - b
The precision of the result value depends on the type of b.
If b is a Float, the precision of the result is Float::DIG+1.
If b is a BigDecimal, the precision of the result is b‘s precision of internal representation from platform. So, it’s return value is platform dependent.
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, DBLE_FIG, 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,VpCreateRbObject(VpBaseFig() + 1, "0"));
VpAddSub(c, a, b, -1);
}
else {
GUARD_OBJ(c,VpCreateRbObject(mx *(VpBaseFig() + 1), "0"));
if (!mx) {
VpSetInf(c,VpGetSign(a));
}
else {
VpAddSub(c, a, b, -1);
}
}
return ToValue(c);
}
Return the negation of self.
-BigDecimal('5') #=> -0.5e1
static VALUE
BigDecimal_neg(VALUE self)
{
ENTER(5);
Real *c, *a;
GUARD_OBJ(a, GetVpValue(self, 1));
GUARD_OBJ(c, VpCreateRbObject(a->Prec *(VpBaseFig() + 1), "0"));
VpAsgn(c, a, -1);
return ToValue(c);
}
Divide by the specified value.
See BigDecimal#div.
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(&c, &res, &div, self, r);
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], (BDIGIT)(VpBaseVal() * (BDIGIT_DBL)res->frac[0] / div->frac[0]));
}
return ToValue(c);
}
Returns true if a is less than b.
Values may be coerced to perform the comparison (see ==, BigDecimal#coerce).
static VALUE
BigDecimal_lt(VALUE self, VALUE r)
{
return BigDecimalCmp(self, r, '<');
}
Returns true if a is less than or equal to b.
Values may be coerced to perform the comparison (see ==, BigDecimal#coerce).
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 a is greater than b.
Values may be coerced to perform the comparison (see ==, BigDecimal#coerce).
static VALUE
BigDecimal_gt(VALUE self, VALUE r)
{
return BigDecimalCmp(self, r, '>');
}
Returns true if a is greater than or equal to b.
Values may be coerced to perform the comparison (see ==, BigDecimal#coerce)
static VALUE
BigDecimal_ge(VALUE self, VALUE r)
{
return BigDecimalCmp(self, r, 'G');
}
Method used to provide marshalling support.
inf = BigDecimal('Infinity') #=> Infinity BigDecimal._load(inf._dump) #=> Infinity
See the Marshal module.
static VALUE
BigDecimal_dump(int argc, VALUE *argv, VALUE self)
{
ENTER(5);
Real *vp;
char *psz;
VALUE dummy;
volatile VALUE dump;
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);
sprintf(psz, "%"PRIuSIZE":", VpMaxPrec(vp)*VpBaseFig());
VpToString(vp, psz+strlen(psz), 0, 0);
rb_str_resize(dump, strlen(psz));
return dump;
}
Returns the absolute value, as a BigDecimal.
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, VpCreateRbObject(mx, "0"));
VpAsgn(c, a, 1);
VpChangeSign(c, 1);
return ToValue(c);
}
Add the specified value.
e.g.
c = a.add(b,n) c = a + b
- 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_add2(VALUE self, VALUE b, VALUE n)
{
ENTER(2);
Real *cv;
SIGNED_VALUE mx = GetPrecisionInt(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 ToValue(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, VpCreateRbObject(mx, "0"));
VpSetPrecLimit(pl);
VpActiveRound(c, a, VP_ROUND_CEIL, iLoc);
if (argc == 0) {
return BigDecimal_to_i(ToValue(c));
}
return ToValue(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, DBLE_FIG, 1));
obj = rb_assoc_new(ToValue(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.
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(ToValue(div), ToValue(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, VpCreateRbObject(mx, "0"));
VpActiveRound(c, a, VP_ROUND_DOWN, 0); /* 0: round off */
return ToValue(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, VpCreateRbObject(mx, "0"));
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(ToValue(c));
}
return ToValue(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, VpCreateRbObject(mx, "0"));
VpFrac(c, a);
return ToValue(c);
}
Creates a hash for this BigDecimal.
Two BigDecimals with equal sign, fractional part and exponent have the same hash.
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(BDIGIT)*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), 0, 0);
rb_str_resize(str, strlen(RSTRING_PTR(str)));
return str;
}
Multiply by the specified value.
e.g.
c = a.mult(b,n) c = a * b
- 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_mult2(VALUE self, VALUE b, VALUE n)
{
ENTER(2);
Real *cv;
SIGNED_VALUE mx = GetPrecisionInt(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 ToValue(cv);
}
}
static VALUE
BigDecimal_n_significant_digits(VALUE self)
{
ENTER(1);
Real *p;
GUARD_OBJ(p, GetVpValue(self, 1));
ssize_t n = p->Prec;
while (n > 0 && p->frac[n-1] == 0) --n;
if (n <= 0) {
return INT2FIX(0);
}
int nlz, ntz;
BDIGIT x = p->frac[0];
for (nlz = BASE_FIG; x > 0; x /= 10) --nlz;
x = p->frac[n-1];
for (ntz = 0; x > 0 && x % 10 == 0; x /= 10) ++ntz;
ssize_t n_digits = BASE_FIG * n - nlz - ntz;
return SSIZET2NUM(n_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 = VpCreateRbObject(n, "0");
RB_GC_GUARD(y->obj);
VpSetNaN(y);
return ToValue(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 += DBLE_FIG;
}
exp = GetVpValueWithPrec(vexp, DBLE_FIG, 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 = VpCreateRbObject(n, "#0");
RB_GC_GUARD(y->obj);
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);
}
return ToValue(y);
}
else if (is_zero(vexp)) {
return ToValue(VpCreateRbObject(n, "1"));
}
else {
return ToValue(VpCreateRbObject(n, "0"));
}
}
if (is_zero(vexp)) {
return ToValue(VpCreateRbObject(n, "1"));
}
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 ToValue(VpCreateRbObject(n, "0"));
}
else {
/* (-Infinity) ** (-odd_integer) -> -0 */
return ToValue(VpCreateRbObject(n, "-0"));
}
}
else {
/* (-Infinity) ** (-non_integer) -> -0 */
return ToValue(VpCreateRbObject(n, "-0"));
}
}
else {
return ToValue(VpCreateRbObject(n, "0"));
}
}
else {
y = VpCreateRbObject(n, "0");
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 ToValue(y);
}
}
if (exp != NULL) {
return rmpd_power_by_big_decimal(x, exp, n);
}
else if (RB_TYPE_P(vexp, T_BIGNUM)) {
VALUE abs_value = BigDecimal_abs(self);
if (is_one(abs_value)) {
return ToValue(VpCreateRbObject(n, "1"));
}
else if (RTEST(rb_funcall(abs_value, '<', 1, INT2FIX(1)))) {
if (is_negative(vexp)) {
y = VpCreateRbObject(n, "0");
if (is_even(vexp)) {
VpSetInf(y, VpGetSign(x));
}
else {
VpSetInf(y, -VpGetSign(x));
}
return ToValue(y);
}
else if (BIGDECIMAL_NEGATIVE_P(x) && is_even(vexp)) {
return ToValue(VpCreateRbObject(n, "-0"));
}
else {
return ToValue(VpCreateRbObject(n, "0"));
}
}
else {
if (is_positive(vexp)) {
y = VpCreateRbObject(n, "0");
if (is_even(vexp)) {
VpSetInf(y, VpGetSign(x));
}
else {
VpSetInf(y, -VpGetSign(x));
}
return ToValue(y);
}
else if (BIGDECIMAL_NEGATIVE_P(x) && is_even(vexp)) {
return ToValue(VpCreateRbObject(n, "-0"));
}
else {
return ToValue(VpCreateRbObject(n, "0"));
}
}
}
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, VpCreateRbObject(mp * (ma + 1), "0"));
}
else {
GUARD_OBJ(y, VpCreateRbObject(1, "0"));
}
VpPower(y, x, int_exp);
if (!NIL_P(prec) && VpIsDef(y)) {
VpMidRound(y, VpGetRoundMode(), n);
}
return ToValue(y);
}
Returns the number of decimal digits in this number.
Example:
BigDecimal("0").precision # => 0 BigDecimal("1").precision # => 1 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)
{
ENTER(1);
Real *p;
GUARD_OBJ(p, GetVpValue(self, 1));
/*
* The most significant digit is frac[0], and the least significant digit is frac[Prec-1].
* When the exponent is zero, the decimal point is located just before frac[0].
* When the exponent is negative, the decimal point moves to leftward.
* Conversely, when the exponent is positive, the decimal point moves to rightward.
*
* | frac[0] frac[1] frac[2] . frac[3] frac[4] ... frac[Prec-1]
* |------------------------> exponent == 3
*/
ssize_t ex = p->exponent;
ssize_t precision = 0;
if (ex < 0) {
precision = (-ex + 1) * BASE_FIG; /* 1 is for p->frac[0] */
ex = 0;
}
else if (p->Prec > 0) {
BDIGIT x = p->frac[0];
for (precision = 0; x > 0; x /= 10) {
++precision;
}
}
if (ex > (ssize_t)p->Prec) {
precision += (ex - 1) * BASE_FIG;
}
else if (p->Prec > 0) {
ssize_t n = (ssize_t)p->Prec - 1;
while (n > 0 && p->frac[n] == 0) --n;
precision += n * BASE_FIG;
if (ex < (ssize_t)p->Prec) {
BDIGIT x = p->frac[n];
for (; x > 0 && x % 10 == 0; x /= 10) {
--precision;
}
}
}
return SSIZET2NUM(precision);
}
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.
BigDecimal('5').precs #=> [9, 18]
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;
}
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 ToValue(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, VpCreateRbObject(mx, "0"));
VpSetPrecLimit(pl);
VpActiveRound(c, a, sw, iLoc);
if (round_to_int) {
return BigDecimal_to_i(ToValue(c));
}
return ToValue(c);
}
Returns the sign of the value.
Returns a positive value if > 0, a negative value if < 0, and a zero if == 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);
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 = GetPrecisionInt(nFig) + VpDblFig() + BASE_FIG;
if (mx <= n) mx = n;
GUARD_OBJ(c, VpCreateRbObject(mx, "0"));
VpSqrt(c, a);
return ToValue(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 = GetPrecisionInt(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 ToValue(cv);
}
}
Returns self.
require 'bigdecimal/util' d = BigDecimal("3.14") d.to_d # => 0.314e1
# File bigdecimal/lib/bigdecimal/util.rb, line 106 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 86 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, 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) * (BDIGIT_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 fractional digits.
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('-123.45678901234567890').to_s('5F') #=> '-123.45678 90123 45678 9' BigDecimal('123.45678901234567890').to_s('+8F') #=> '+123.45678901 23456789' BigDecimal('123.45678901234567890').to_s(' F') #=> ' 123.4567890123456789'
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, mc, fPlus);
}
else {
VpToString (vp, psz, 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, VpCreateRbObject(mx, "0"));
VpSetPrecLimit(pl);
VpActiveRound(c, a, VP_ROUND_DOWN, iLoc); /* 0: truncate */
if (argc == 0) {
return BigDecimal_to_i(ToValue(c));
}
return ToValue(c);
}
Returns True if the value is zero.
static VALUE
BigDecimal_zero(VALUE self)
{
Real *a = GetVpValue(self, 1);
return VpIsZero(a) ? Qtrue : Qfalse;
}