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Merge 1d7e626cc6 into b080fcd3cd

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Yusuke Endoh 2025-08-15 02:19:11 +05:30 • committed by GitHub
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70
math.c
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@ -457,6 +457,33 @@ math_exp(VALUE unused_obj, VALUE x)
return DBL2NUM(exp(Get_Double(x)));
}
/*
* call-seq:
* Math.expm1(x) -> float
*
* Returns +e+ raised to the +x+ power minus 1.
*
* - Domain: <tt>[-INFINITY, INFINITY]</tt>.
* - Range: <tt>[-1.0, INFINITY]</tt>.
*
* Examples:
*
* expm1(-INFINITY) # => 0.0
* expm1(-1.0) # => -0.6321205588285577 # 1.0/E - 1
* expm1(0.0) # => 0.0
* expm1(0.5) # => 0.6487212707001282 # sqrt(E) - 1
* expm1(1.0) # => 1.718281828459045 # E - 1
* expm1(2.0) # => 6.38905609893065 # E**2 - 1
* expm1(INFINITY) # => Infinity
*
*/
static VALUE
math_expm1(VALUE unused_obj, VALUE x)
{
return DBL2NUM(expm1(Get_Double(x)));
}
#if defined __CYGWIN__
# include <cygwin/version.h>
# if CYGWIN_VERSION_DLL_MAJOR < 1005
@ -646,6 +673,47 @@ math_log10(VALUE unused_obj, VALUE x)
return DBL2NUM(log10(d) + numbits * log10(2)); /* log10(d * 2 ** numbits) */
}
/*
* call-seq:
* Math.log1p(x) -> float
*
* Returns the base E {logarithm}[https://en.wikipedia.org/wiki/Logarithm] of +x+ + 1.
*
* - Domain: <tt>[-1, INFINITY]</tt>.
* - Range: <tt>[-INFINITY, INFINITY]</tt>.
*
* Examples:
*
* log1p(-1.0) # => -Infinity
* log1p(0.0) # => 0.0
* log1p(E - 1) # => 1.0
* log1p(INFINITY) # => Infinity
*
*/
static VALUE
math_log1p(VALUE unused_obj, VALUE x)
{
size_t numbits;
double d = get_double_rshift(x, &numbits);
if (numbits != 0) {
x = rb_big_plus(x, INT2FIX(1));
d = math_log_split(x, &numbits);
/* check for pole error */
if (d == 0.0) return DBL2NUM(-HUGE_VAL);
d = log(d);
d += numbits * M_LN2;
return DBL2NUM(d);
}
domain_check_min(d, -1.0, "log1p");
/* check for pole error */
if (d == -1.0) return DBL2NUM(-HUGE_VAL);
return DBL2NUM(log1p(d)); /* log10(d * 2 ** numbits) */
}
static VALUE rb_math_sqrt(VALUE x);
/*
@ -1120,9 +1188,11 @@ InitVM_Math(void)
rb_define_module_function(rb_mMath, "atanh", math_atanh, 1);
rb_define_module_function(rb_mMath, "exp", math_exp, 1);
rb_define_module_function(rb_mMath, "expm1", math_expm1, 1);
rb_define_module_function(rb_mMath, "log", math_log, -1);
rb_define_module_function(rb_mMath, "log2", math_log2, 1);
rb_define_module_function(rb_mMath, "log10", math_log10, 1);
rb_define_module_function(rb_mMath, "log1p", math_log1p, 1);
rb_define_module_function(rb_mMath, "sqrt", math_sqrt, 1);
rb_define_module_function(rb_mMath, "cbrt", math_cbrt, 1);

20
test/ruby/test_math.rb
View file

@ -147,6 +147,13 @@ class TestMath < Test::Unit::TestCase
check(Math::E ** 2, Math.exp(2))
end
def test_expm1
check(0, Math.expm1(0))
check(Math.sqrt(Math::E) - 1, Math.expm1(0.5))
check(Math::E - 1, Math.expm1(1))
check(Math::E ** 2 - 1, Math.expm1(2))
end
def test_log
check(0, Math.log(1))
check(1, Math.log(Math::E))
@ -201,6 +208,19 @@ class TestMath < Test::Unit::TestCase
assert_nothing_raised { assert_infinity(-Math.log10(0)) }
end
def test_log1p
check(0, Math.log1p(0))
check(1, Math.log1p(Math::E - 1))
check(Math.log(2.0 ** 64 + 1), Math.log1p(1 << 64))
check(Math.log(2) * 1024.0, Math.log1p(2 ** 1024))
assert_nothing_raised { assert_infinity(Math.log1p(1.0/0)) }
assert_nothing_raised { assert_infinity(-Math.log1p(-1.0)) }
assert_raise_with_message(Math::DomainError, /\blog1p\b/) { Math.log1p(-1.1) }
assert_raise_with_message(Math::DomainError, /\blog1p\b/) { Math.log1p(-Float::EPSILON-1) }
assert_nothing_raised { assert_nan(Math.log1p(Float::NAN)) }
assert_nothing_raised { assert_infinity(-Math.log1p(-1)) }
end
def test_sqrt
check(0, Math.sqrt(0))
check(1, Math.sqrt(1))