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Class: BigDecimal

Relationships & Source Files
Super Chains via Extension / Inclusion / Inheritance
Class Chain:
self, ::Numeric
Instance Chain:
self, ::Numeric
Inherits: Numeric
Defined in: ext/bigdecimal/bigdecimal.c,
ext/bigdecimal/bigdecimal.c,
ext/bigdecimal/lib/bigdecimal/util.rb

Overview

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 .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 (C) 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.

Constant Summary

Class Method Summary

Instance Attribute Summary

Instance Method Summary

Class Method Details

._load(str)

Internal method used to provide marshalling support. See the Marshal module.

[ GitHub ]

  
# File 'ext/bigdecimal/bigdecimal.c', line 435

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);
}

.double_fig

The 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.

[ GitHub ]

  
# File 'ext/bigdecimal/bigdecimal.c', line 345

static VALUE
BigDecimal_double_fig(VALUE self)
{
    return INT2FIX(VpDblFig());
}

.interpret_loosely(str)

[ GitHub ]

  
# File 'ext/bigdecimal/bigdecimal.c', line 2776

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(digits)

Limit the number of significant digits in newly created BigDecimal numbers to the specified value. Rounding is performed as necessary, as specified by .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.

[ GitHub ]

  
# File 'ext/bigdecimal/bigdecimal.c', line 2802

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;
}

.mode(mode, value)

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:

EXCEPTION_NaN EXCEPTION_INFINITY EXCEPTION_UNDERFLOW EXCEPTION_OVERFLOW EXCEPTION_ZERODIVIDE 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: 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)

[ GitHub ]

  
# File 'ext/bigdecimal/bigdecimal.c', line 583

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;
}

.save_exception_mode

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 .mode

[ GitHub ]

  
# File 'ext/bigdecimal/bigdecimal.c', line 2861

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;
}

.save_limit

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
[ GitHub ]

  
# File 'ext/bigdecimal/bigdecimal.c', line 2911

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;
}

.save_rounding_mode

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 .mode

[ GitHub ]

  
# File 'ext/bigdecimal/bigdecimal.c', line 2886

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;
}

Instance Attribute Details

#finite?Boolean (readonly)

Returns True if the value is finite (not NaN or infinite).

[ GitHub ]

  
# File 'ext/bigdecimal/bigdecimal.c', line 726

static VALUE
BigDecimal_IsFinite(VALUE self)
{
    Real *p = GetVpValue(self, 1);
    if (VpIsNaN(p)) return Qfalse;
    if (VpIsInf(p)) return Qfalse;
    return Qtrue;
}

#infinite?Boolean (readonly)

Returns nil, -1, or 1 depending on whether the value is finite, -Infinity, or Infinity.

[ GitHub ]

  
# File 'ext/bigdecimal/bigdecimal.c', line 716

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;
}

#nan?Boolean (readonly)

Returns True if the value is Not a Number.

[ GitHub ]

  
# File 'ext/bigdecimal/bigdecimal.c', line 705

static VALUE
BigDecimal_IsNaN(VALUE self)
{
    Real *p = GetVpValue(self, 1);
    if (VpIsNaN(p))  return Qtrue;
    return Qfalse;
}

#nonzero?Boolean (readonly)

Returns self if the value is non-zero, nil otherwise.

[ GitHub ]

  
# File 'ext/bigdecimal/bigdecimal.c', line 1154

static VALUE
BigDecimal_nonzero(VALUE self)
{
    Real *a = GetVpValue(self, 1);
    return VpIsZero(a) ? Qnil : self;
}

#zero?Boolean (readonly)

Returns True if the value is zero.

[ GitHub ]

  
# File 'ext/bigdecimal/bigdecimal.c', line 1146

static VALUE
BigDecimal_zero(VALUE self)
{
    Real *a = GetVpValue(self, 1);
    return VpIsZero(a) ? Qtrue : Qfalse;
}

Instance Method Details

#%

[ GitHub ]

#mult(value, digits)

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.

[ GitHub ]

  
# File 'ext/bigdecimal/bigdecimal.c', line 1273

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, DBL_DIG+1, 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);
}

#**(n) ⇒ BigDecimal

Returns the value raised to the power of n.

See #power.

[ GitHub ]

  
# File 'ext/bigdecimal/bigdecimal.c', line 2560

static VALUE
BigDecimal_power_op(VALUE self, VALUE exp)
{
    return BigDecimal_power(1, &exp, self);
}

#add(value, digits)

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.

[ GitHub ]

  
# File 'ext/bigdecimal/bigdecimal.c', line 952

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, DBL_DIG+1, 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);
}

#+big_decimal

Return self.

+BigDecimal('5')  #=> 0.5e1
[ GitHub ]

  
# File 'ext/bigdecimal/bigdecimal.c', line 929

static VALUE
BigDecimal_uplus(VALUE self)
{
    return self;
}

#-(b) ⇒ BigDecimal

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.

[ GitHub ]

  
# File 'ext/bigdecimal/bigdecimal.c', line 1010

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, DBL_DIG+1, 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);
}

#-big_decimal

Return the negation of self.

-BigDecimal('5')  #=> -0.5e1
[ GitHub ]

  
# File 'ext/bigdecimal/bigdecimal.c', line 1247

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);
}

#/

[ GitHub ]

#<(b)

Returns true if a is less than b.

Values may be coerced to perform the comparison (see ==, #coerce).

[ GitHub ]

  
# File 'ext/bigdecimal/bigdecimal.c', line 1193

static VALUE
BigDecimal_lt(VALUE self, VALUE r)
{
    return BigDecimalCmp(self, r, '<');
}

#<=(b)

Returns true if a is less than or equal to b.

Values may be coerced to perform the comparison (see ==, #coerce).

[ GitHub ]

  
# File 'ext/bigdecimal/bigdecimal.c', line 1206

static VALUE
BigDecimal_le(VALUE self, VALUE r)
{
    return BigDecimalCmp(self, r, 'L');
}

#<=>(r)

The comparison operator. a <=> b is 0 if a == b, 1 if a > b, -1 if a < b.

[ GitHub ]

  
# File 'ext/bigdecimal/bigdecimal.c', line 1164

static VALUE
BigDecimal_comp(VALUE self, VALUE r)
{
    return BigDecimalCmp(self, r, '*');
}

#==(r) Also known as: #===, #eql?

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
[ GitHub ]

  
# File 'ext/bigdecimal/bigdecimal.c', line 1180

static VALUE
BigDecimal_eq(VALUE self, VALUE r)
{
    return BigDecimalCmp(self, r, '=');
}

#===(r)

Alias for #==.

#>(b)

Returns true if a is greater than b.

Values may be coerced to perform the comparison (see ==, #coerce).

[ GitHub ]

  
# File 'ext/bigdecimal/bigdecimal.c', line 1219

static VALUE
BigDecimal_gt(VALUE self, VALUE r)
{
    return BigDecimalCmp(self, r, '>');
}

#>=(b)

Returns true if a is greater than or equal to b.

Values may be coerced to perform the comparison (see ==, #coerce)

[ GitHub ]

  
# File 'ext/bigdecimal/bigdecimal.c', line 1232

static VALUE
BigDecimal_ge(VALUE self, VALUE r)
{
    return BigDecimalCmp(self, r, 'G');
}

#_dump

Method used to provide marshalling support.

inf = BigDecimal('Infinity')
  #=> Infinity
BigDecimal._load(inf._dump)
  #=> Infinity

See the Marshal module.

[ GitHub ]

  
# File 'ext/bigdecimal/bigdecimal.c', line 413

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;
}

#absbig_decimal

Returns the absolute value, as a BigDecimal.

BigDecimal('5').abs  #=> 0.5e1
BigDecimal('-3').abs #=> 0.3e1
[ GitHub ]

  
# File 'ext/bigdecimal/bigdecimal.c', line 1723

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(value, digits)

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.

[ GitHub ]

  
# File 'ext/bigdecimal/bigdecimal.c', line 1648

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);
    }
}

#ceil(n)

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
[ GitHub ]

  
# File 'ext/bigdecimal/bigdecimal.c', line 1978

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);
}

#clone

Alias for #dup.

#coerce(other)

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.

[ GitHub ]

  
# File 'ext/bigdecimal/bigdecimal.c', line 895

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, DBL_DIG+1, 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;
}

#div(value, digits) ⇒ BigDecimal, Integer

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
[ GitHub ]

  
# File 'ext/bigdecimal/bigdecimal.c', line 1638

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);
}

#divmod(value)

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.

[ GitHub ]

  
# File 'ext/bigdecimal/bigdecimal.c', line 1552

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"));
}

#dup Also known as: #clone

[ GitHub ]

  
# File 'ext/bigdecimal/bigdecimal.c', line 2582

static VALUE
BigDecimal_clone(VALUE self)
{
  return self;
}

#eql?(r)

Alias for #==.

#exponent

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.

[ GitHub ]

  
# File 'ext/bigdecimal/bigdecimal.c', line 2169

static VALUE
BigDecimal_exponent(VALUE self)
{
    ssize_t e = VpExponent10(GetVpValue(self, 1));
    return SSIZET2NUM(e);
}

#fix

Return the integer part of the number, as a BigDecimal.

[ GitHub ]

  
# File 'ext/bigdecimal/bigdecimal.c', line 1764

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);
}

#floor(n)

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
[ GitHub ]

  
# File 'ext/bigdecimal/bigdecimal.c', line 1931

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);
}

#frac

Return the fractional part of the number, as a BigDecimal.

[ GitHub ]

  
# File 'ext/bigdecimal/bigdecimal.c', line 1900

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);
}

#hash

Creates a hash for this BigDecimal.

Two BigDecimals with equal sign, fractional part and exponent have the same hash.

[ GitHub ]

  
# File 'ext/bigdecimal/bigdecimal.c', line 384

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);
}

#inspect

Returns a string representation of self.

BigDecimal("1234.5678").inspect
  #=> "0.12345678e4"
[ GitHub ]

  
# File 'ext/bigdecimal/bigdecimal.c', line 2181

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;
}

#modulo

[ GitHub ]

#mult(value, digits)

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.

[ GitHub ]

  
# File 'ext/bigdecimal/bigdecimal.c', line 1696

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);
    }
}

#power(n) #power(n, prec)

Returns the value raised to the power of n.

Note that n must be an ::Integer.

Also available as the operator **.

[ GitHub ]

  
# File 'ext/bigdecimal/bigdecimal.c', line 2324

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;
	}
	exp = GetVpValueWithPrec(vexp, DBL_DIG+1, 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);
	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;
	    }
	    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);
}

#precsArray

Returns an Array of two ::Integer values.

The first value is the current number of significant digits in the BigDecimal. The second value is the maximum number of significant digits for the BigDecimal.

BigDecimal('5').precs #=> [9, 18]
[ GitHub ]

  
# File 'ext/bigdecimal/bigdecimal.c', line 363

static VALUE
BigDecimal_prec(VALUE self)
{
    ENTER(1);
    Real *p;
    VALUE obj;

    GUARD_OBJ(p, GetVpValue(self, 1));
    obj = rb_assoc_new(SIZET2NUM(p->Prec*VpBaseFig()),
		       SIZET2NUM(p->MaxPrec*VpBaseFig()));
    return obj;
}

#quo

[ GitHub ]

#remainder

[ GitHub ]

#round(n, mode)

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.

BigDecimal('3.14159').round(3) #=> 3.142
BigDecimal('13345.234').round(-2) #=> 13300.0

The value of the optional mode argument can be used to determine how rounding is performed; see .mode.

[ GitHub ]

  
# File 'ext/bigdecimal/bigdecimal.c', line 1803

static VALUE
BigDecimal_round(int argc, VALUE *argv, VALUE self)
{
    ENTER(5);
    Real   *c, *a;
    int    iLoc = 0;
    VALUE  vLoc;
    VALUE  vRound;
    size_t mx, pl;

    unsigned short sw = VpGetRoundMode();

    switch (rb_scan_args(argc, argv, "02", &vLoc, &vRound)) {
      case 0:
	iLoc = 0;
	break;
      case 1:
        if (RB_TYPE_P(vLoc, T_HASH)) {
	    sw = check_rounding_mode_option(vLoc);
	}
	else {
	    iLoc = NUM2INT(vLoc);
	}
	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 (argc == 0) {
	return BigDecimal_to_i(ToValue(c));
    }
    return ToValue(c);
}

#sign

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

[ GitHub ]

  
# File 'ext/bigdecimal/bigdecimal.c', line 2836

static VALUE
BigDecimal_sign(VALUE self)
{ /* sign */
    int s = GetVpValue(self, 1)->sign;
    return INT2FIX(s);
}

#split

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.)

[ GitHub ]

  
# File 'ext/bigdecimal/bigdecimal.c', line 2132

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;
}

#sqrt(n)

Returns the square root of the value.

Result has at least n significant digits.

[ GitHub ]

  
# File 'ext/bigdecimal/bigdecimal.c', line 1745

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);
}

#sub(value, digits) ⇒ BigDecimal

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.

[ GitHub ]

  
# File 'ext/bigdecimal/bigdecimal.c', line 1678

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);
    }
}

#to_dBigDecimal

Returns self.

require 'bigdecimal/util'

d = BigDecimal("3.14")
d.to_d                       # => 0.314e1
[ GitHub ]

  
# File 'ext/bigdecimal/lib/bigdecimal/util.rb', line 106

def to_d
  self
end

#to_digitsString

Converts a BigDecimal to a ::String of the form “nnnnnn.mmm”. This method is deprecated; use #to_s(“F”) instead.

require 'bigdecimal/util'

d = BigDecimal("3.14")
d.to_digits                  # => "3.14"
[ GitHub ]

  
# File 'ext/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

#to_f

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.

[ GitHub ]

  
# File 'ext/bigdecimal/bigdecimal.c', line 802

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);
}

#to_i Also known as: #to_int

Returns the value as an ::Integer.

If the BigDecimal is infinity or NaN, raises FloatDomainError.

[ GitHub ]

  
# File 'ext/bigdecimal/bigdecimal.c', line 755

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;
    }
}

#to_int

Alias for #to_i.

#to_r

Converts a BigDecimal to a ::Rational.

[ GitHub ]

  
# File 'ext/bigdecimal/bigdecimal.c', line 849

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))));
    }
}

#to_s(s) ⇒ ?

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'
[ GitHub ]

  
# File 'ext/bigdecimal/bigdecimal.c', line 2037

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(n)

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
[ GitHub ]

  
# File 'ext/bigdecimal/bigdecimal.c', line 1871

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);
}