BigDecimal extends the native Float class to provide the to_d method.
When you require BigDecimal in your application, this method will be available on Float objects.
Float objects represent inexact real numbers using the native architecture’s double-precision floating point representation.
Floating point has a different arithmetic and is an inexact number. So you should know its esoteric system. see following:
Represents the rounding mode for floating point addition.
Usually defaults to 1, rounding to the nearest number.
Other modes include:
- -1
-
Indeterminable
- 0
-
Rounding towards zero
- 1
-
Rounding to the nearest number
- 2
-
Rounding towards positive infinity
- 3
-
Rounding towards negative infinity
The base of the floating point, or number of unique digits used to represent the number.
Usually defaults to 2 on most systems, which would represent a base-10 decimal.
The number of base digits for the double data type.
Usually defaults to 53.
The minimum number of significant decimal digits in a double-precision floating point.
Usually defaults to 15.
The smallest posable exponent value in a double-precision floating point.
Usually defaults to -1021.
The largest possible exponent value in a double-precision floating point.
Usually defaults to 1024.
The smallest negative exponent in a double-precision floating point where 10 raised to this power minus 1.
Usually defaults to -307.
The largest positive exponent in a double-precision floating point where 10 raised to this power minus 1.
Usually defaults to 308.
The smallest positive normalized number in a double-precision floating point.
Usually defaults to 2.2250738585072014e-308.
If the platform supports denormalized numbers, there are numbers between zero and Float::MIN. 0.0.next_float returns the smallest positive floating point number including denormalized numbers.
The largest possible integer in a double-precision floating point number.
Usually defaults to 1.7976931348623157e+308.
The difference between 1 and the smallest double-precision floating point number greater than 1.
Usually defaults to 2.2204460492503131e-16.
An expression representing positive infinity.
An expression representing a value which is “not a number”.
static VALUE
flo_mod(VALUE x, VALUE y)
{
double fy;
if (RB_TYPE_P(y, T_FIXNUM)) {
fy = (double)FIX2LONG(y);
}
else if (RB_TYPE_P(y, T_BIGNUM)) {
fy = rb_big2dbl(y);
}
else if (RB_TYPE_P(y, T_FLOAT)) {
fy = RFLOAT_VALUE(y);
}
else {
return rb_num_coerce_bin(x, y, '%');
}
return DBL2NUM(ruby_float_mod(RFLOAT_VALUE(x), fy));
}
Return the modulo after division of float by other.
6543.21.modulo(137) #=> 104.21 6543.21.modulo(137.24) #=> 92.9299999999996
static VALUE
flo_mul(VALUE x, VALUE y)
{
if (RB_TYPE_P(y, T_FIXNUM)) {
return DBL2NUM(RFLOAT_VALUE(x) * (double)FIX2LONG(y));
}
else if (RB_TYPE_P(y, T_BIGNUM)) {
return DBL2NUM(RFLOAT_VALUE(x) * rb_big2dbl(y));
}
else if (RB_TYPE_P(y, T_FLOAT)) {
return DBL2NUM(RFLOAT_VALUE(x) * RFLOAT_VALUE(y));
}
else {
return rb_num_coerce_bin(x, y, '*');
}
}
Returns a new float which is the product of float and other.
static VALUE
flo_pow(VALUE x, VALUE y)
{
double dx, dy;
if (RB_TYPE_P(y, T_FIXNUM)) {
dx = RFLOAT_VALUE(x);
dy = (double)FIX2LONG(y);
}
else if (RB_TYPE_P(y, T_BIGNUM)) {
dx = RFLOAT_VALUE(x);
dy = rb_big2dbl(y);
}
else if (RB_TYPE_P(y, T_FLOAT)) {
dx = RFLOAT_VALUE(x);
dy = RFLOAT_VALUE(y);
if (dx < 0 && dy != round(dy))
return rb_funcall(rb_complex_raw1(x), idPow, 1, y);
}
else {
return rb_num_coerce_bin(x, y, idPow);
}
return DBL2NUM(pow(dx, dy));
}
float ** other -> float
Raises float to the power of other.
2.0**3 #=> 8.0
static VALUE
flo_plus(VALUE x, VALUE y)
{
if (RB_TYPE_P(y, T_FIXNUM)) {
return DBL2NUM(RFLOAT_VALUE(x) + (double)FIX2LONG(y));
}
else if (RB_TYPE_P(y, T_BIGNUM)) {
return DBL2NUM(RFLOAT_VALUE(x) + rb_big2dbl(y));
}
else if (RB_TYPE_P(y, T_FLOAT)) {
return DBL2NUM(RFLOAT_VALUE(x) + RFLOAT_VALUE(y));
}
else {
return rb_num_coerce_bin(x, y, '+');
}
}
Returns a new float which is the sum of float and other.
static VALUE
flo_minus(VALUE x, VALUE y)
{
if (RB_TYPE_P(y, T_FIXNUM)) {
return DBL2NUM(RFLOAT_VALUE(x) - (double)FIX2LONG(y));
}
else if (RB_TYPE_P(y, T_BIGNUM)) {
return DBL2NUM(RFLOAT_VALUE(x) - rb_big2dbl(y));
}
else if (RB_TYPE_P(y, T_FLOAT)) {
return DBL2NUM(RFLOAT_VALUE(x) - RFLOAT_VALUE(y));
}
else {
return rb_num_coerce_bin(x, y, '-');
}
}
Returns a new float which is the difference of float and other.
static VALUE
flo_uminus(VALUE flt)
{
return DBL2NUM(-RFLOAT_VALUE(flt));
}
Returns float, negated.
static VALUE
flo_div(VALUE x, VALUE y)
{
long f_y;
double d;
if (RB_TYPE_P(y, T_FIXNUM)) {
f_y = FIX2LONG(y);
return DBL2NUM(RFLOAT_VALUE(x) / (double)f_y);
}
else if (RB_TYPE_P(y, T_BIGNUM)) {
d = rb_big2dbl(y);
return DBL2NUM(RFLOAT_VALUE(x) / d);
}
else if (RB_TYPE_P(y, T_FLOAT)) {
return DBL2NUM(RFLOAT_VALUE(x) / RFLOAT_VALUE(y));
}
else {
return rb_num_coerce_bin(x, y, '/');
}
}
Returns a new float which is the result of dividing float by other.
static VALUE
flo_lt(VALUE x, VALUE y)
{
double a, b;
a = RFLOAT_VALUE(x);
if (RB_TYPE_P(y, T_FIXNUM) || RB_TYPE_P(y, T_BIGNUM)) {
VALUE rel = rb_integer_float_cmp(y, x);
if (FIXNUM_P(rel))
return -FIX2INT(rel) < 0 ? Qtrue : Qfalse;
return Qfalse;
}
else if (RB_TYPE_P(y, T_FLOAT)) {
b = RFLOAT_VALUE(y);
#if defined(_MSC_VER) && _MSC_VER < 1300
if (isnan(b)) return Qfalse;
#endif
}
else {
return rb_num_coerce_relop(x, y, '<');
}
#if defined(_MSC_VER) && _MSC_VER < 1300
if (isnan(a)) return Qfalse;
#endif
return (a < b)?Qtrue:Qfalse;
}
Returns true if float is less than real.
The result of NaN < NaN is undefined, so the implementation-dependent value is returned.
static VALUE
flo_le(VALUE x, VALUE y)
{
double a, b;
a = RFLOAT_VALUE(x);
if (RB_TYPE_P(y, T_FIXNUM) || RB_TYPE_P(y, T_BIGNUM)) {
VALUE rel = rb_integer_float_cmp(y, x);
if (FIXNUM_P(rel))
return -FIX2INT(rel) <= 0 ? Qtrue : Qfalse;
return Qfalse;
}
else if (RB_TYPE_P(y, T_FLOAT)) {
b = RFLOAT_VALUE(y);
#if defined(_MSC_VER) && _MSC_VER < 1300
if (isnan(b)) return Qfalse;
#endif
}
else {
return rb_num_coerce_relop(x, y, idLE);
}
#if defined(_MSC_VER) && _MSC_VER < 1300
if (isnan(a)) return Qfalse;
#endif
return (a <= b)?Qtrue:Qfalse;
}
Returns true if float is less than or equal to real.
The result of NaN <= NaN is undefined, so the implementation-dependent value is returned.
static VALUE
flo_cmp(VALUE x, VALUE y)
{
double a, b;
VALUE i;
a = RFLOAT_VALUE(x);
if (isnan(a)) return Qnil;
if (RB_TYPE_P(y, T_FIXNUM) || RB_TYPE_P(y, T_BIGNUM)) {
VALUE rel = rb_integer_float_cmp(y, x);
if (FIXNUM_P(rel))
return INT2FIX(-FIX2INT(rel));
return rel;
}
else if (RB_TYPE_P(y, T_FLOAT)) {
b = RFLOAT_VALUE(y);
}
else {
if (isinf(a) && (i = rb_check_funcall(y, rb_intern("infinite?"), 0, 0)) != Qundef) {
if (RTEST(i)) {
int j = rb_cmpint(i, x, y);
j = (a > 0.0) ? (j > 0 ? 0 : +1) : (j < 0 ? 0 : -1);
return INT2FIX(j);
}
if (a > 0.0) return INT2FIX(1);
return INT2FIX(-1);
}
return rb_num_coerce_cmp(x, y, id_cmp);
}
return rb_dbl_cmp(a, b);
}
Returns -1, 0, +1 or nil depending on whether float is less than, equal to, or greater than real. This is the basis for the tests in Comparable.
The result of NaN <=> NaN is undefined, so the implementation-dependent value is returned.
nil is returned if the two values are incomparable.
static VALUE
flo_eq(VALUE x, VALUE y)
{
volatile double a, b;
if (RB_TYPE_P(y, T_FIXNUM) || RB_TYPE_P(y, T_BIGNUM)) {
return rb_integer_float_eq(y, x);
}
else if (RB_TYPE_P(y, T_FLOAT)) {
b = RFLOAT_VALUE(y);
#if defined(_MSC_VER) && _MSC_VER < 1300
if (isnan(b)) return Qfalse;
#endif
}
else {
return num_equal(x, y);
}
a = RFLOAT_VALUE(x);
#if defined(_MSC_VER) && _MSC_VER < 1300
if (isnan(a)) return Qfalse;
#endif
return (a == b)?Qtrue:Qfalse;
}
Returns true only if obj has the same value as float. Contrast this with Float#eql?, which requires obj to be a Float.
The result of NaN == NaN is undefined, so the implementation-dependent value is returned.
1.0 == 1 #=> true
static VALUE
flo_gt(VALUE x, VALUE y)
{
double a, b;
a = RFLOAT_VALUE(x);
if (RB_TYPE_P(y, T_FIXNUM) || RB_TYPE_P(y, T_BIGNUM)) {
VALUE rel = rb_integer_float_cmp(y, x);
if (FIXNUM_P(rel))
return -FIX2INT(rel) > 0 ? Qtrue : Qfalse;
return Qfalse;
}
else if (RB_TYPE_P(y, T_FLOAT)) {
b = RFLOAT_VALUE(y);
#if defined(_MSC_VER) && _MSC_VER < 1300
if (isnan(b)) return Qfalse;
#endif
}
else {
return rb_num_coerce_relop(x, y, '>');
}
#if defined(_MSC_VER) && _MSC_VER < 1300
if (isnan(a)) return Qfalse;
#endif
return (a > b)?Qtrue:Qfalse;
}
Returns true if float is greater than real.
The result of NaN > NaN is undefined, so the implementation-dependent value is returned.
static VALUE
flo_ge(VALUE x, VALUE y)
{
double a, b;
a = RFLOAT_VALUE(x);
if (RB_TYPE_P(y, T_FIXNUM) || RB_TYPE_P(y, T_BIGNUM)) {
VALUE rel = rb_integer_float_cmp(y, x);
if (FIXNUM_P(rel))
return -FIX2INT(rel) >= 0 ? Qtrue : Qfalse;
return Qfalse;
}
else if (RB_TYPE_P(y, T_FLOAT)) {
b = RFLOAT_VALUE(y);
#if defined(_MSC_VER) && _MSC_VER < 1300
if (isnan(b)) return Qfalse;
#endif
}
else {
return rb_num_coerce_relop(x, y, idGE);
}
#if defined(_MSC_VER) && _MSC_VER < 1300
if (isnan(a)) return Qfalse;
#endif
return (a >= b)?Qtrue:Qfalse;
}
Returns true if float is greater than or equal to real.
The result of NaN >= NaN is undefined, so the implementation-dependent value is returned.
static VALUE
flo_abs(VALUE flt)
{
double val = fabs(RFLOAT_VALUE(flt));
return DBL2NUM(val);
}
Returns the absolute value of float.
(-34.56).abs #=> 34.56 -34.56.abs #=> 34.56
static VALUE
float_arg(VALUE self)
{
if (isnan(RFLOAT_VALUE(self)))
return self;
if (f_tpositive_p(self))
return INT2FIX(0);
return rb_const_get(rb_mMath, id_PI);
}
Returns 0 if the value is positive, pi otherwise.
static VALUE
flo_ceil(VALUE num)
{
double f = ceil(RFLOAT_VALUE(num));
long val;
if (!FIXABLE(f)) {
return rb_dbl2big(f);
}
val = (long)f;
return LONG2FIX(val);
}
Returns the smallest Integer greater than or equal to float.
1.2.ceil #=> 2 2.0.ceil #=> 2 (-1.2).ceil #=> -1 (-2.0).ceil #=> -2
static VALUE
flo_coerce(VALUE x, VALUE y)
{
return rb_assoc_new(rb_Float(y), x);
}
# File tmp/rubies/ruby-2.3.8/lib/rexml/xpath_parser.rb, line 28
def dclone ; self ; end
provides a unified clone operation, for REXML::XPathParser to use across multiple Object types
static VALUE
float_denominator(VALUE self)
{
double d = RFLOAT_VALUE(self);
if (isinf(d) || isnan(d))
return INT2FIX(1);
return rb_call_super(0, 0);
}
Returns the denominator (always positive). The result is machine dependent.
See numerator.
static VALUE
flo_divmod(VALUE x, VALUE y)
{
double fy, div, mod;
volatile VALUE a, b;
if (RB_TYPE_P(y, T_FIXNUM)) {
fy = (double)FIX2LONG(y);
}
else if (RB_TYPE_P(y, T_BIGNUM)) {
fy = rb_big2dbl(y);
}
else if (RB_TYPE_P(y, T_FLOAT)) {
fy = RFLOAT_VALUE(y);
}
else {
return rb_num_coerce_bin(x, y, id_divmod);
}
flodivmod(RFLOAT_VALUE(x), fy, &div, &mod);
a = dbl2ival(div);
b = DBL2NUM(mod);
return rb_assoc_new(a, b);
}
See Numeric#divmod.
42.0.divmod 6 #=> [7, 0.0] 42.0.divmod 5 #=> [8, 2.0]
static VALUE
flo_eql(VALUE x, VALUE y)
{
if (RB_TYPE_P(y, T_FLOAT)) {
double a = RFLOAT_VALUE(x);
double b = RFLOAT_VALUE(y);
#if defined(_MSC_VER) && _MSC_VER < 1300
if (isnan(a) || isnan(b)) return Qfalse;
#endif
if (a == b)
return Qtrue;
}
return Qfalse;
}
static VALUE
flo_is_finite_p(VALUE num)
{
double value = RFLOAT_VALUE(num);
#ifdef HAVE_ISFINITE
if (!isfinite(value))
return Qfalse;
#else
if (isinf(value) || isnan(value))
return Qfalse;
#endif
return Qtrue;
}
Returns true if float is a valid IEEE floating point number (it is not infinite, and Float#nan? is false).
static VALUE
flo_floor(VALUE num)
{
double f = floor(RFLOAT_VALUE(num));
long val;
if (!FIXABLE(f)) {
return rb_dbl2big(f);
}
val = (long)f;
return LONG2FIX(val);
}
Returns the largest integer less than or equal to float.
1.2.floor #=> 1 2.0.floor #=> 2 (-1.2).floor #=> -2 (-2.0).floor #=> -2
static VALUE
flo_hash(VALUE num)
{
return rb_dbl_hash(RFLOAT_VALUE(num));
}
Returns a hash code for this float.
See also Object#hash.
static VALUE
flo_is_infinite_p(VALUE num)
{
double value = RFLOAT_VALUE(num);
if (isinf(value)) {
return INT2FIX( value < 0 ? -1 : 1 );
}
return Qnil;
}
Return values corresponding to the value of float:
finite-
nil -Infinity-
-1 +Infinity-
1
For example:
(0.0).infinite? #=> nil (-1.0/0.0).infinite? #=> -1 (+1.0/0.0).infinite? #=> 1
static VALUE
flo_is_nan_p(VALUE num)
{
double value = RFLOAT_VALUE(num);
return isnan(value) ? Qtrue : Qfalse;
}
Returns true if float is an invalid IEEE floating point number.
a = -1.0 #=> -1.0 a.nan? #=> false a = 0.0/0.0 #=> NaN a.nan? #=> true
static VALUE
flo_negative_p(VALUE num)
{
double f = RFLOAT_VALUE(num);
return f < 0.0 ? Qtrue : Qfalse;
}
Returns true if float is less than 0.
static VALUE
flo_next_float(VALUE vx)
{
double x, y;
x = NUM2DBL(vx);
y = nextafter(x, INFINITY);
return DBL2NUM(y);
}
Returns the next representable floating-point number.
Float::MAX.next_float and Float::INFINITY.next_float is Float::INFINITY.
Float::NAN.next_float is Float::NAN.
For example:
p 0.01.next_float #=> 0.010000000000000002 p 1.0.next_float #=> 1.0000000000000002 p 100.0.next_float #=> 100.00000000000001 p 0.01.next_float - 0.01 #=> 1.734723475976807e-18 p 1.0.next_float - 1.0 #=> 2.220446049250313e-16 p 100.0.next_float - 100.0 #=> 1.4210854715202004e-14 f = 0.01; 20.times { printf "%-20a %s\n", f, f.to_s; f = f.next_float } #=> 0x1.47ae147ae147bp-7 0.01 # 0x1.47ae147ae147cp-7 0.010000000000000002 # 0x1.47ae147ae147dp-7 0.010000000000000004 # 0x1.47ae147ae147ep-7 0.010000000000000005 # 0x1.47ae147ae147fp-7 0.010000000000000007 # 0x1.47ae147ae148p-7 0.010000000000000009 # 0x1.47ae147ae1481p-7 0.01000000000000001 # 0x1.47ae147ae1482p-7 0.010000000000000012 # 0x1.47ae147ae1483p-7 0.010000000000000014 # 0x1.47ae147ae1484p-7 0.010000000000000016 # 0x1.47ae147ae1485p-7 0.010000000000000018 # 0x1.47ae147ae1486p-7 0.01000000000000002 # 0x1.47ae147ae1487p-7 0.010000000000000021 # 0x1.47ae147ae1488p-7 0.010000000000000023 # 0x1.47ae147ae1489p-7 0.010000000000000024 # 0x1.47ae147ae148ap-7 0.010000000000000026 # 0x1.47ae147ae148bp-7 0.010000000000000028 # 0x1.47ae147ae148cp-7 0.01000000000000003 # 0x1.47ae147ae148dp-7 0.010000000000000031 # 0x1.47ae147ae148ep-7 0.010000000000000033 f = 0.0 100.times { f += 0.1 } p f #=> 9.99999999999998 # should be 10.0 in the ideal world. p 10-f #=> 1.9539925233402755e-14 # the floating-point error. p(10.0.next_float-10) #=> 1.7763568394002505e-15 # 1 ulp (units in the last place). p((10-f)/(10.0.next_float-10)) #=> 11.0 # the error is 11 ulp. p((10-f)/(10*Float::EPSILON)) #=> 8.8 # approximation of the above. p "%a" % f #=> "0x1.3fffffffffff5p+3" # the last hex digit is 5. 16 - 5 = 11 ulp.
static VALUE
float_numerator(VALUE self)
{
double d = RFLOAT_VALUE(self);
if (isinf(d) || isnan(d))
return self;
return rb_call_super(0, 0);
}
Returns the numerator. The result is machine dependent.
n = 0.3.numerator #=> 5404319552844595 d = 0.3.denominator #=> 18014398509481984 n.fdiv(d) #=> 0.3
static VALUE
flo_positive_p(VALUE num)
{
double f = RFLOAT_VALUE(num);
return f > 0.0 ? Qtrue : Qfalse;
}
Returns true if float is greater than 0.
static VALUE
flo_prev_float(VALUE vx)
{
double x, y;
x = NUM2DBL(vx);
y = nextafter(x, -INFINITY);
return DBL2NUM(y);
}
Returns the previous representable floating-point number.
(-Float::MAX).prev_float and (-Float::INFINITY).prev_float is -Float::INFINITY.
Float::NAN.prev_float is Float::NAN.
For example:
p 0.01.prev_float #=> 0.009999999999999998 p 1.0.prev_float #=> 0.9999999999999999 p 100.0.prev_float #=> 99.99999999999999 p 0.01 - 0.01.prev_float #=> 1.734723475976807e-18 p 1.0 - 1.0.prev_float #=> 1.1102230246251565e-16 p 100.0 - 100.0.prev_float #=> 1.4210854715202004e-14 f = 0.01; 20.times { printf "%-20a %s\n", f, f.to_s; f = f.prev_float } #=> 0x1.47ae147ae147bp-7 0.01 # 0x1.47ae147ae147ap-7 0.009999999999999998 # 0x1.47ae147ae1479p-7 0.009999999999999997 # 0x1.47ae147ae1478p-7 0.009999999999999995 # 0x1.47ae147ae1477p-7 0.009999999999999993 # 0x1.47ae147ae1476p-7 0.009999999999999992 # 0x1.47ae147ae1475p-7 0.00999999999999999 # 0x1.47ae147ae1474p-7 0.009999999999999988 # 0x1.47ae147ae1473p-7 0.009999999999999986 # 0x1.47ae147ae1472p-7 0.009999999999999985 # 0x1.47ae147ae1471p-7 0.009999999999999983 # 0x1.47ae147ae147p-7 0.009999999999999981 # 0x1.47ae147ae146fp-7 0.00999999999999998 # 0x1.47ae147ae146ep-7 0.009999999999999978 # 0x1.47ae147ae146dp-7 0.009999999999999976 # 0x1.47ae147ae146cp-7 0.009999999999999974 # 0x1.47ae147ae146bp-7 0.009999999999999972 # 0x1.47ae147ae146ap-7 0.00999999999999997 # 0x1.47ae147ae1469p-7 0.009999999999999969 # 0x1.47ae147ae1468p-7 0.009999999999999967
static VALUE
flo_quo(VALUE x, VALUE y)
{
return rb_funcall(x, '/', 1, y);
}
Returns float / numeric, same as Float#/.
static VALUE
float_rationalize(int argc, VALUE *argv, VALUE self)
{
VALUE e;
if (f_negative_p(self))
return f_negate(float_rationalize(argc, argv, f_abs(self)));
rb_scan_args(argc, argv, "01", &e);
if (argc != 0) {
return rb_flt_rationalize_with_prec(self, e);
}
else {
return rb_flt_rationalize(self);
}
}
Returns a simpler approximation of the value (flt-|eps| <= result <= flt+|eps|). if the optional eps is not given, it will be chosen automatically.
0.3.rationalize #=> (3/10) 1.333.rationalize #=> (1333/1000) 1.333.rationalize(0.01) #=> (4/3)
See to_r.
static VALUE
flo_round(int argc, VALUE *argv, VALUE num)
{
VALUE nd;
double number, f, x;
int ndigits = 0;
int binexp;
enum {float_dig = DBL_DIG+2};
if (argc > 0 && rb_scan_args(argc, argv, "01", &nd) == 1) {
ndigits = NUM2INT(nd);
}
if (ndigits < 0) {
return int_round_0(flo_truncate(num), ndigits);
}
number = RFLOAT_VALUE(num);
if (ndigits == 0) {
return dbl2ival(number);
}
frexp(number, &binexp);
/* Let `exp` be such that `number` is written as:"0.#{digits}e#{exp}",
i.e. such that 10 ** (exp - 1) <= |number| < 10 ** exp
Recall that up to float_dig digits can be needed to represent a double,
so if ndigits + exp >= float_dig, the intermediate value (number * 10 ** ndigits)
will be an integer and thus the result is the original number.
If ndigits + exp <= 0, the result is 0 or "1e#{exp}", so
if ndigits + exp < 0, the result is 0.
We have:
2 ** (binexp-1) <= |number| < 2 ** binexp
10 ** ((binexp-1)/log_2(10)) <= |number| < 10 ** (binexp/log_2(10))
If binexp >= 0, and since log_2(10) = 3.322259:
10 ** (binexp/4 - 1) < |number| < 10 ** (binexp/3)
floor(binexp/4) <= exp <= ceil(binexp/3)
If binexp <= 0, swap the /4 and the /3
So if ndigits + floor(binexp/(4 or 3)) >= float_dig, the result is number
If ndigits + ceil(binexp/(3 or 4)) < 0 the result is 0
*/
if (isinf(number) || isnan(number) ||
(ndigits >= float_dig - (binexp > 0 ? binexp / 4 : binexp / 3 - 1))) {
return num;
}
if (ndigits < - (binexp > 0 ? binexp / 3 + 1 : binexp / 4)) {
return DBL2NUM(0);
}
f = pow(10, ndigits);
x = round(number * f);
if (x > 0) {
if ((double)((x + 0.5) / f) <= number) x += 1;
}
else {
if ((double)((x - 0.5) / f) >= number) x -= 1;
}
return DBL2NUM(x / f);}
/*
* call-seq:
* float.to_i -> integer
* float.to_int -> integer
* float.truncate -> integer
*
* Returns the +float+ truncated to an Integer.
*
* Synonyms are #to_i, #to_int, and #truncate.
*/
static VALUE
flo_truncate(VALUE num)
{
double f = RFLOAT_VALUE(num);
long val;
if (f > 0.0) f = floor(f);
if (f < 0.0) f = ceil(f);
if (!FIXABLE(f)) {
return rb_dbl2big(f);
}
val = (long)f;
return LONG2FIX(val);
}
Rounds float to a given precision in decimal digits (default 0 digits).
Precision may be negative. Returns a floating point number when ndigits is more than zero.
1.4.round #=> 1 1.5.round #=> 2 1.6.round #=> 2 (-1.5).round #=> -2 1.234567.round(2) #=> 1.23 1.234567.round(3) #=> 1.235 1.234567.round(4) #=> 1.2346 1.234567.round(5) #=> 1.23457 34567.89.round(-5) #=> 0 34567.89.round(-4) #=> 30000 34567.89.round(-3) #=> 35000 34567.89.round(-2) #=> 34600 34567.89.round(-1) #=> 34570 34567.89.round(0) #=> 34568 34567.89.round(1) #=> 34567.9 34567.89.round(2) #=> 34567.89 34567.89.round(3) #=> 34567.89
# File tmp/rubies/ruby-2.3.8/ext/bigdecimal/lib/bigdecimal/util.rb, line 39
def to_d(precision=nil)
BigDecimal(self, precision || Float::DIG)
end
Convert flt to a BigDecimal and return it.
require 'bigdecimal' require 'bigdecimal/util' 0.5.to_d # => #<BigDecimal:1dc69e0,'0.5E0',9(18)>
static VALUE
flo_to_f(VALUE num)
{
return num;
}
Since float is already a float, returns self.
static VALUE
flo_truncate(VALUE num)
{
double f = RFLOAT_VALUE(num);
long val;
if (f > 0.0) f = floor(f);
if (f < 0.0) f = ceil(f);
if (!FIXABLE(f)) {
return rb_dbl2big(f);
}
val = (long)f;
return LONG2FIX(val);
}
static VALUE
float_to_r(VALUE self)
{
VALUE f, n;
float_decode_internal(self, &f, &n);
#if FLT_RADIX == 2
{
long ln = FIX2LONG(n);
if (ln == 0)
return f_to_r(f);
if (ln > 0)
return f_to_r(f_lshift(f, n));
ln = -ln;
return rb_rational_new2(f, f_lshift(ONE, INT2FIX(ln)));
}
#else
return f_to_r(f_mul(f, f_expt(INT2FIX(FLT_RADIX), n)));
#endif
}
Returns the value as a rational.
NOTE: 0.3.to_r isn’t the same as ‘0.3’.to_r. The latter is equivalent to ‘3/10’.to_r, but the former isn’t so.
2.0.to_r #=> (2/1) 2.5.to_r #=> (5/2) -0.75.to_r #=> (-3/4) 0.0.to_r #=> (0/1)
See rationalize.
static VALUE
flo_to_s(VALUE flt)
{
enum {decimal_mant = DBL_MANT_DIG-DBL_DIG};
enum {float_dig = DBL_DIG+1};
char buf[float_dig + (decimal_mant + CHAR_BIT - 1) / CHAR_BIT + 10];
double value = RFLOAT_VALUE(flt);
VALUE s;
char *p, *e;
int sign, decpt, digs;
if (isinf(value))
return rb_usascii_str_new2(value < 0 ? "-Infinity" : "Infinity");
else if (isnan(value))
return rb_usascii_str_new2("NaN");
p = ruby_dtoa(value, 0, 0, &decpt, &sign, &e);
s = sign ? rb_usascii_str_new_cstr("-") : rb_usascii_str_new(0, 0);
if ((digs = (int)(e - p)) >= (int)sizeof(buf)) digs = (int)sizeof(buf) - 1;
memcpy(buf, p, digs);
xfree(p);
if (decpt > 0) {
if (decpt < digs) {
memmove(buf + decpt + 1, buf + decpt, digs - decpt);
buf[decpt] = '.';
rb_str_cat(s, buf, digs + 1);
}
else if (decpt <= DBL_DIG) {
long len;
char *ptr;
rb_str_cat(s, buf, digs);
rb_str_resize(s, (len = RSTRING_LEN(s)) + decpt - digs + 2);
ptr = RSTRING_PTR(s) + len;
if (decpt > digs) {
memset(ptr, '0', decpt - digs);
ptr += decpt - digs;
}
memcpy(ptr, ".0", 2);
}
else {
goto exp;
}
}
else if (decpt > -4) {
long len;
char *ptr;
rb_str_cat(s, "0.", 2);
rb_str_resize(s, (len = RSTRING_LEN(s)) - decpt + digs);
ptr = RSTRING_PTR(s);
memset(ptr += len, '0', -decpt);
memcpy(ptr -= decpt, buf, digs);
}
else {
exp:
if (digs > 1) {
memmove(buf + 2, buf + 1, digs - 1);
}
else {
buf[2] = '0';
digs++;
}
buf[1] = '.';
rb_str_cat(s, buf, digs + 1);
rb_str_catf(s, "e%+03d", decpt - 1);
}
return s;
}
Returns a string containing a representation of self. As well as a fixed or exponential form of the float, the call may return NaN, Infinity, and -Infinity.
static VALUE
flo_zero_p(VALUE num)
{
if (RFLOAT_VALUE(num) == 0.0) {
return Qtrue;
}
return Qfalse;
}
Returns true if float is 0.0.