class Float - RDoc Documentation (original) (raw)

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:

• docs.oracle.com/cd/E19957-01/806-3568/ncg_goldberg.html
• github.com/rdp/ruby_tutorials_core/wiki/Ruby-Talk-FAQ#floats_imprecise
• en.wikipedia.org/wiki/Floating_point#Accuracy_problems

Constants

DIG

The minimum number of significant decimal digits in a double-precision floating point.

Usually defaults to 15.

EPSILON

The difference between 1 and the smallest double-precision floating point number greater than 1.

Usually defaults to 2.2204460492503131e-16.

INFINITY

An expression representing positive infinity.

MANT_DIG

The number of base digits for the double data type.

Usually defaults to 53.

MAX

The largest possible integer in a double-precision floating point number.

Usually defaults to 1.7976931348623157e+308.

MAX_10_EXP

The largest positive exponent in a double-precision floating point where 10 raised to this power minus 1.

Usually defaults to 308.

MAX_EXP

The largest possible exponent value in a double-precision floating point.

Usually defaults to 1024.

MIN

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.

MIN_10_EXP

The smallest negative exponent in a double-precision floating point where 10 raised to this power minus 1.

Usually defaults to -307.

MIN_EXP

The smallest possible exponent value in a double-precision floating point.

Usually defaults to -1021.

NAN

An expression representing a value which is “not a number”.

RADIX

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.

Public Instance Methods

float % other → float click to toggle source

Returns the modulo after division of float by other.

6543.21.modulo(137)
6543.21.modulo(137.24)

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));

}

float * other → float click to toggle source

Returns a new Float which is the product of float and other.

VALUE rb_float_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, '*'); } }

float ** other → float click to toggle source

Raises float to the power of other.

2.0**3

VALUE rb_float_pow(VALUE x, VALUE y) { double dx, dy; if (y == INT2FIX(2)) { dx = RFLOAT_VALUE(x); return DBL2NUM(dx * dx); } else 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_dbl_complex_new_polar_pi(pow(-dx, dy), dy); } else { return rb_num_coerce_bin(x, y, idPow); } return DBL2NUM(pow(dx, dy)); }

float + other → float click to toggle source

Returns a new Float which is the sum of float and other.

VALUE rb_float_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, '+'); } }

float - other → float click to toggle source

Returns a new Float which is the difference of float and other.

VALUE rb_float_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, '-'); } }

-float → float click to toggle source

Returns float, negated.

VALUE rb_float_uminus(VALUE flt) { return DBL2NUM(-RFLOAT_VALUE(flt)); }

float / other → float click to toggle source

Returns a new Float which is the result of dividing float by other.

VALUE rb_float_div(VALUE x, VALUE y) { double num = RFLOAT_VALUE(x); double den; double ret;

if (RB_TYPE_P(y, T_FIXNUM)) {
    den = FIX2LONG(y);
}
else if (RB_TYPE_P(y, T_BIGNUM)) {
    den = rb_big2dbl(y);
}
else if (RB_TYPE_P(y, T_FLOAT)) {
    den = RFLOAT_VALUE(y);
}
else {
    return rb_num_coerce_bin(x, y, '/');
}

ret = double_div_double(num, den);
return DBL2NUM(ret);

}

float < real → true or false click to toggle source

Returns true if float is less than real.

The result of NaN < NaN is undefined, so an implementation-dependent value is returned.

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 -FIX2LONG(rel) < 0 ? Qtrue : Qfalse;
    return Qfalse;
}
else if (RB_TYPE_P(y, T_FLOAT)) {
    b = RFLOAT_VALUE(y);

#if MSC_VERSION_BEFORE(1300) if (isnan(b)) return Qfalse; #endif } else { return rb_num_coerce_relop(x, y, '<'); } #if MSC_VERSION_BEFORE(1300) if (isnan(a)) return Qfalse; #endif return (a < b)?Qtrue:Qfalse; }

float <= real → true or false click to toggle source

Returns true if float is less than or equal to real.

The result of NaN <= NaN is undefined, so an 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 -FIX2LONG(rel) <= 0 ? Qtrue : Qfalse;
    return Qfalse;
}
else if (RB_TYPE_P(y, T_FLOAT)) {
    b = RFLOAT_VALUE(y);

#if MSC_VERSION_BEFORE(1300) if (isnan(b)) return Qfalse; #endif } else { return rb_num_coerce_relop(x, y, idLE); } #if MSC_VERSION_BEFORE(1300) if (isnan(a)) return Qfalse; #endif return (a <= b)?Qtrue:Qfalse; }

float <=> real → -1, 0, +1, or nil click to toggle source

Returns -1, 0, or +1 depending on whether float is less than, equal to, or greater than real. This is the basis for the tests in the Comparable module.

The result of NaN <=> NaN is undefined, so an implementation-dependent value is returned.

nil is returned if the two values are incomparable.

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 LONG2FIX(-FIX2LONG(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);

}

float == obj → true or false click to toggle source

Returns true only if obj has the same value as float. Contrast this with Float#eql?, which requires obj to be a Float.

1.0 == 1

The result of NaN == NaN is undefined, so an implementation-dependent value is returned.

MJIT_FUNC_EXPORTED VALUE rb_float_equal(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 MSC_VERSION_BEFORE(1300) if (isnan(b)) return Qfalse; #endif } else { return num_equal(x, y); } a = RFLOAT_VALUE(x); #if MSC_VERSION_BEFORE(1300) if (isnan(a)) return Qfalse; #endif return (a == b)?Qtrue:Qfalse; }

Also aliased as: ===

Returns true only if obj has the same value as float. Contrast this with Float#eql?, which requires obj to be a Float.

1.0 == 1

The result of NaN == NaN is undefined, so an implementation-dependent value is returned.

Alias for: ==

float > real → true or false click to toggle source

Returns true if float is greater than real.

The result of NaN > NaN is undefined, so an implementation-dependent value is returned.

VALUE rb_float_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 -FIX2LONG(rel) > 0 ? Qtrue : Qfalse;
    return Qfalse;
}
else if (RB_TYPE_P(y, T_FLOAT)) {
    b = RFLOAT_VALUE(y);

#if MSC_VERSION_BEFORE(1300) if (isnan(b)) return Qfalse; #endif } else { return rb_num_coerce_relop(x, y, '>'); } #if MSC_VERSION_BEFORE(1300) if (isnan(a)) return Qfalse; #endif return (a > b)?Qtrue:Qfalse; }

float >= real → true or false click to toggle source

Returns true if float is greater than or equal to real.

The result of NaN >= NaN is undefined, so an 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 -FIX2LONG(rel) >= 0 ? Qtrue : Qfalse;
    return Qfalse;
}
else if (RB_TYPE_P(y, T_FLOAT)) {
    b = RFLOAT_VALUE(y);

#if MSC_VERSION_BEFORE(1300) if (isnan(b)) return Qfalse; #endif } else { return rb_num_coerce_relop(x, y, idGE); } #if MSC_VERSION_BEFORE(1300) if (isnan(a)) return Qfalse; #endif return (a >= b)?Qtrue:Qfalse; }

abs → float click to toggle source

Returns the absolute value of float.

(-34.56).abs
-34.56.abs
34.56.abs

Float#magnitude is an alias for Float#abs.

VALUE rb_float_abs(VALUE flt) { double val = fabs(RFLOAT_VALUE(flt)); return DBL2NUM(val); }

angle → 0 or float

Returns 0 if the value is positive, pi otherwise.

Alias for: arg

arg → 0 or float click to toggle source

Returns 0 if the value is positive, pi otherwise.

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); }

ceil([ndigits]) → integer or float click to toggle source

Returns the smallest number greater than or equal to float with a precision of ndigits decimal digits (default: 0).

When the precision is negative, the returned value is an integer with at least ndigits.abs trailing zeros.

Returns a floating point number when ndigits is positive, otherwise returns an integer.

1.2.ceil
2.0.ceil
(-1.2).ceil
(-2.0).ceil

1.234567.ceil(2)
1.234567.ceil(3)
1.234567.ceil(4)
1.234567.ceil(5)

34567.89.ceil(-5)
34567.89.ceil(-4)
34567.89.ceil(-3)
34567.89.ceil(-2)
34567.89.ceil(-1)
34567.89.ceil(0)
34567.89.ceil(1)
34567.89.ceil(2)
34567.89.ceil(3)

Note that the limited precision of floating point arithmetic might lead to surprising results:

(2.1 / 0.7).ceil

static VALUE flo_ceil(int argc, VALUE *argv, VALUE num) { int ndigits = 0;

if (rb_check_arity(argc, 0, 1)) {
    ndigits = NUM2INT(argv[0]);
}
return rb_float_ceil(num, ndigits);

}

coerce(numeric) → array click to toggle source

Returns an array with both numeric and float represented as Float objects.

This is achieved by converting numeric to a Float.

1.2.coerce(3)
2.5.coerce(1.1)

static VALUE flo_coerce(VALUE x, VALUE y) { return rb_assoc_new(rb_Float(y), x); }

denominator → integer click to toggle source

Returns the denominator (always positive). The result is machine dependent.

See also Float#numerator.

VALUE rb_float_denominator(VALUE self) { double d = RFLOAT_VALUE(self); VALUE r; if (isinf(d) || isnan(d)) return INT2FIX(1); r = float_to_r(self); return nurat_denominator(r); }

divmod(numeric) → array click to toggle source

See Numeric#divmod.

42.0.divmod(6)
42.0.divmod(5)

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);

}

eql?(obj) → true or false click to toggle source

Returns true only if obj is a Float with the same value as float. Contrast this with Float#==, which performs type conversions.

1.0.eql?(1)

The result of NaN.eql?(NaN) is undefined, so an implementation-dependent value is returned.

MJIT_FUNC_EXPORTED VALUE rb_float_eql(VALUE x, VALUE y) { if (RB_TYPE_P(y, T_FLOAT)) { double a = RFLOAT_VALUE(x); double b = RFLOAT_VALUE(y); #if MSC_VERSION_BEFORE(1300) if (isnan(a) || isnan(b)) return Qfalse; #endif if (a == b) return Qtrue; } return Qfalse; }

fdiv(numeric) → float

Returns float / numeric, same as Float#/.

Alias for: quo

finite? → true or false click to toggle source

Returns true if float is a valid IEEE floating point number, i.e. it is not infinite and Float#nan? is false.

VALUE rb_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;

}

floor([ndigits]) → integer or float click to toggle source

Returns the largest number less than or equal to float with a precision of ndigits decimal digits (default: 0).

When the precision is negative, the returned value is an integer with at least ndigits.abs trailing zeros.

Returns a floating point number when ndigits is positive, otherwise returns an integer.

1.2.floor
2.0.floor
(-1.2).floor
(-2.0).floor

1.234567.floor(2)
1.234567.floor(3)
1.234567.floor(4)
1.234567.floor(5)

34567.89.floor(-5)
34567.89.floor(-4)
34567.89.floor(-3)
34567.89.floor(-2)
34567.89.floor(-1)
34567.89.floor(0)
34567.89.floor(1)
34567.89.floor(2)
34567.89.floor(3)

Note that the limited precision of floating point arithmetic might lead to surprising results:

(0.3 / 0.1).floor

static VALUE flo_floor(int argc, VALUE *argv, VALUE num) { int ndigits = 0; if (rb_check_arity(argc, 0, 1)) { ndigits = NUM2INT(argv[0]); } return rb_float_floor(num, ndigits); }

hash → integer click to toggle source

Returns a hash code for this float.

See also Object#hash.

static VALUE flo_hash(VALUE num) { return rb_dbl_hash(RFLOAT_VALUE(num)); }

infinite? → -1, 1, or nil click to toggle source

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

(0.0).infinite?
(-1.0/0.0).infinite?
(+1.0/0.0).infinite?

VALUE rb_flo_is_infinite_p(VALUE num) { double value = RFLOAT_VALUE(num);

if (isinf(value)) {
    return INT2FIX( value < 0 ? -1 : 1 );
}

return Qnil;

}

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.

magnitude → float

Alias for: abs

modulo(other) → float

Returns the modulo after division of float by other.

6543.21.modulo(137)
6543.21.modulo(137.24)

Alias for: %

nan? → true or false click to toggle source

Returns true if float is an invalid IEEE floating point number.

a = -1.0
a.nan?
a = 0.0/0.0
a.nan?

static VALUE flo_is_nan_p(VALUE num) { double value = RFLOAT_VALUE(num);

return isnan(value) ? Qtrue : Qfalse;

}

negative? → true or false click to toggle source

Returns true if float is less than 0.

static VALUE flo_negative_p(VALUE num) { double f = RFLOAT_VALUE(num); return f < 0.0 ? Qtrue : Qfalse; }

next_float → float click to toggle source

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:

0.01.next_float
1.0.next_float
100.0.next_float

0.01.next_float - 0.01
1.0.next_float - 1.0
100.0.next_float - 100.0

f = 0.01; 20.times { printf "%-20a %s\n", f, f.to_s; f = f.next_float }

f = 0.0 100.times { f += 0.1 } f
10-f
10.0.next_float-10
(10-f)/(10.0.next_float-10) (10-f)/(10*Float::EPSILON)
"%a" % 10
"%a" % f

static VALUE flo_next_float(VALUE vx) { return flo_nextafter(vx, HUGE_VAL); }

numerator → integer click to toggle source

Returns the numerator. The result is machine dependent.

n = 0.3.numerator
d = 0.3.denominator
n.fdiv(d)

See also Float#denominator.

VALUE rb_float_numerator(VALUE self) { double d = RFLOAT_VALUE(self); VALUE r; if (isinf(d) || isnan(d)) return self; r = float_to_r(self); return nurat_numerator(r); }

phase → 0 or float

Returns 0 if the value is positive, pi otherwise.

Alias for: arg

positive? → true or false click to toggle source

Returns true if float is greater than 0.

static VALUE flo_positive_p(VALUE num) { double f = RFLOAT_VALUE(num); return f > 0.0 ? Qtrue : Qfalse; }

prev_float → float click to toggle source

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:

0.01.prev_float
1.0.prev_float
100.0.prev_float

0.01 - 0.01.prev_float
1.0 - 1.0.prev_float
100.0 - 100.0.prev_float

f = 0.01; 20.times { printf "%-20a %s\n", f, f.to_s; f = f.prev_float }

static VALUE flo_prev_float(VALUE vx) { return flo_nextafter(vx, -HUGE_VAL); }

quo(numeric) → float click to toggle source

Returns float / numeric, same as Float#/.

static VALUE flo_quo(VALUE x, VALUE y) { return num_funcall1(x, '/', y); }

Also aliased as: fdiv

rationalize([eps]) → rational click to toggle source

Returns a simpler approximation of the value (flt-|eps| <= result <= flt+|eps|). If the optional argument eps is not given, it will be chosen automatically.

0.3.rationalize
1.333.rationalize
1.333.rationalize(0.01)

See also Float#to_r.

static VALUE float_rationalize(int argc, VALUE *argv, VALUE self) { double d = RFLOAT_VALUE(self); VALUE rat; int neg = d < 0.0; if (neg) self = DBL2NUM(-d);

if (rb_check_arity(argc, 0, 1)) {
    rat = rb_flt_rationalize_with_prec(self, argv[0]);
}
else {
    rat = rb_flt_rationalize(self);
}
if (neg) RATIONAL_SET_NUM(rat, rb_int_uminus(RRATIONAL(rat)->num));
return rat;

}

round([ndigits] [, half: mode]) → integer or float click to toggle source

Returns float rounded to the nearest value with a precision of ndigits decimal digits (default: 0).

When the precision is negative, the returned value is an integer with at least ndigits.abs trailing zeros.

Returns a floating point number when ndigits is positive, otherwise returns an integer.

1.4.round
1.5.round
1.6.round
(-1.5).round

1.234567.round(2)
1.234567.round(3)
1.234567.round(4)
1.234567.round(5)

34567.89.round(-5)
34567.89.round(-4)
34567.89.round(-3)
34567.89.round(-2)
34567.89.round(-1)
34567.89.round(0)
34567.89.round(1)
34567.89.round(2)
34567.89.round(3)

If the optional half keyword argument is given, numbers that are half-way between two possible rounded values will be rounded according to the specified tie-breaking mode:

• :up or nil: round half away from zero (default)
• :down: round half toward zero
• :even: round half toward the nearest even number
  2.5.round(half: :up)
  2.5.round(half: :down)
  2.5.round(half: :even)
  3.5.round(half: :up)
  3.5.round(half: :down)
  3.5.round(half: :even)
  (-2.5).round(half: :up)
  (-2.5).round(half: :down)
  (-2.5).round(half: :even)

static VALUE flo_round(int argc, VALUE *argv, VALUE num) { double number, f, x; VALUE nd, opt; int ndigits = 0; enum ruby_num_rounding_mode mode;

if (rb_scan_args(argc, argv, "01:", &nd, &opt)) {
    ndigits = NUM2INT(nd);
}
mode = rb_num_get_rounding_option(opt);
number = RFLOAT_VALUE(num);
if (number == 0.0) {
    return ndigits > 0 ? DBL2NUM(number) : INT2FIX(0);
}
if (ndigits < 0) {
    return rb_int_round(flo_to_i(num), ndigits, mode);
}
if (ndigits == 0) {
    x = ROUND_CALL(mode, round, (number, 1.0));
    return dbl2ival(x);
}
if (isfinite(number)) {
    int binexp;
    frexp(number, &binexp);
    if (float_round_overflow(ndigits, binexp)) return num;
    if (float_round_underflow(ndigits, binexp)) return DBL2NUM(0);
    f = pow(10, ndigits);
    x = ROUND_CALL(mode, round, (number, f));
    return DBL2NUM(x / f);
}
return num;

}

to_d → bigdecimal click to toggle source

to_d(precision) → bigdecimal

Returns the value of float as a BigDecimal. The precision parameter is used to determine the number of significant digits for the result (the default is Float::DIG).

require 'bigdecimal' require 'bigdecimal/util'

0.5.to_d
1.234.to_d(2)

See also BigDecimal::new.

def to_d(precision=Float::DIG+1) BigDecimal(self, precision) end

to_f → self click to toggle source

Since float is already a Float, returns self.

static VALUE flo_to_f(VALUE num) { return num; }

to_i → integer click to toggle source

Returns the float truncated to an Integer.

1.2.to_i
(-1.2).to_i

Note that the limited precision of floating point arithmetic might lead to surprising results:

(0.3 / 0.1).to_i

to_int is an alias for to_i.

static VALUE flo_to_i(VALUE num) { double f = RFLOAT_VALUE(num);

if (f > 0.0) f = floor(f);
if (f < 0.0) f = ceil(f);

return dbl2ival(f);

}

Returns the float truncated to an Integer.

1.2.to_i
(-1.2).to_i

Note that the limited precision of floating point arithmetic might lead to surprising results:

(0.3 / 0.1).to_i

to_int is an alias for to_i.

to_r → rational click to toggle source

Returns the value as a rational.

2.0.to_r
2.5.to_r
-0.75.to_r
0.0.to_r
0.3.to_r

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.

0.3.to_r == 3/10r
"0.3".to_r == 3/10r

See also Float#rationalize.

static VALUE float_to_r(VALUE self) { VALUE f; int n;

float_decode_internal(self, &f, &n);

#if FLT_RADIX == 2 if (n == 0) return rb_rational_new1(f); if (n > 0) return rb_rational_new1(rb_int_lshift(f, INT2FIX(n))); n = -n; return rb_rational_new2(f, rb_int_lshift(ONE, INT2FIX(n))); #else f = rb_int_mul(f, rb_int_pow(INT2FIX(FLT_RADIX), n)); if (RB_TYPE_P(f, T_RATIONAL)) return f; return rb_rational_new1(f); #endif }

to_s → string click to toggle source

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_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)) {
    static const char minf[] = "-Infinity";
    const int pos = (value > 0); /* skip "-" */
    return rb_usascii_str_new(minf+pos, strlen(minf)-pos);
}
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 {
    goto exp;
}
return s;

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; }

truncate([ndigits]) → integer or float click to toggle source

Returns float truncated (toward zero) to a precision of ndigits decimal digits (default: 0).

When the precision is negative, the returned value is an integer with at least ndigits.abs trailing zeros.

Returns a floating point number when ndigits is positive, otherwise returns an integer.

2.8.truncate
(-2.8).truncate
1.234567.truncate(2)
34567.89.truncate(-2)

Note that the limited precision of floating point arithmetic might lead to surprising results:

(0.3 / 0.1).truncate

static VALUE flo_truncate(int argc, VALUE *argv, VALUE num) { if (signbit(RFLOAT_VALUE(num))) return flo_ceil(argc, argv, num); else return flo_floor(argc, argv, num); }

zero? → true or false click to toggle source

Returns true if float is 0.0.

static VALUE flo_zero_p(VALUE num) { return flo_iszero(num) ? Qtrue : Qfalse; }