kotovalexarian-likes-github/ruby--ruby
1
0
Fork 0
mirror of https://github.com/ruby/ruby.git synced 2022-11-09 12:17:21 -05:00
Code Releases Activity
ruby--ruby/math.c
stomar 9638295527 math.c: improve docs for Math.sqrt 
* math.c: [DOC] mention possibly surprising behavior of Math.sqrt
  due to floating point arithmetic; also refer to BigDecimal#sqrt.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@58291 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
2017-04-09 13:30:31 +00:00

1049 lines
22 KiB
C
Raw Blame History

/**********************************************************************
math.c -
$Author$
created at: Tue Jan 25 14:12:56 JST 1994
Copyright (C) 1993-2007 Yukihiro Matsumoto
**********************************************************************/
#ifdef _MSC_VER
# define _USE_MATH_DEFINES 1
#endif
#include "internal.h"
#include <float.h>
#include <math.h>
#include <errno.h>
#if defined(HAVE_SIGNBIT) && defined(__GNUC__) && defined(__sun) && \
!defined(signbit)
extern int signbit(double);
#endif
#define RB_BIGNUM_TYPE_P(x) RB_TYPE_P((x), T_BIGNUM)
VALUE rb_mMath;
VALUE rb_eMathDomainError;
#define Get_Double(x) rb_num_to_dbl(x)
#define domain_error(msg) \
rb_raise(rb_eMathDomainError, "Numerical argument is out of domain - " #msg)
/*
* call-seq:
* Math.atan2(y, x) -> Float
*
* Computes the arc tangent given +y+ and +x+.
* Returns a Float in the range -PI..PI. Return value is a angle
* in radians between the positive x-axis of cartesian plane
* and the point given by the coordinates (+x+, +y+) on it.
*
* Domain: (-INFINITY, INFINITY)
*
* Codomain: [-PI, PI]
*
* Math.atan2(-0.0, -1.0) #=> -3.141592653589793
* Math.atan2(-1.0, -1.0) #=> -2.356194490192345
* Math.atan2(-1.0, 0.0) #=> -1.5707963267948966
* Math.atan2(-1.0, 1.0) #=> -0.7853981633974483
* Math.atan2(-0.0, 1.0) #=> -0.0
* Math.atan2(0.0, 1.0) #=> 0.0
* Math.atan2(1.0, 1.0) #=> 0.7853981633974483
* Math.atan2(1.0, 0.0) #=> 1.5707963267948966
* Math.atan2(1.0, -1.0) #=> 2.356194490192345
* Math.atan2(0.0, -1.0) #=> 3.141592653589793
* Math.atan2(INFINITY, INFINITY) #=> 0.7853981633974483
* Math.atan2(INFINITY, -INFINITY) #=> 2.356194490192345
* Math.atan2(-INFINITY, INFINITY) #=> -0.7853981633974483
* Math.atan2(-INFINITY, -INFINITY) #=> -2.356194490192345
*
*/
static VALUE
math_atan2(VALUE unused_obj, VALUE y, VALUE x)
{
double dx, dy;
dx = Get_Double(x);
dy = Get_Double(y);
if (dx == 0.0 && dy == 0.0) {
if (!signbit(dx))
return DBL2NUM(dy);
if (!signbit(dy))
return DBL2NUM(M_PI);
return DBL2NUM(-M_PI);
}
#ifndef ATAN2_INF_C99
if (isinf(dx) && isinf(dy)) {
/* optimization for FLONUM */
if (dx < 0.0) {
const double dz = (3.0 * M_PI / 4.0);
return (dy < 0.0) ? DBL2NUM(-dz) : DBL2NUM(dz);
}
else {
const double dz = (M_PI / 4.0);
return (dy < 0.0) ? DBL2NUM(-dz) : DBL2NUM(dz);
}
}
#endif
return DBL2NUM(atan2(dy, dx));
}
/*
* call-seq:
* Math.cos(x) -> Float
*
* Computes the cosine of +x+ (expressed in radians).
* Returns a Float in the range -1.0..1.0.
*
* Domain: (-INFINITY, INFINITY)
*
* Codomain: [-1, 1]
*
* Math.cos(Math::PI) #=> -1.0
*
*/
static VALUE
math_cos(VALUE unused_obj, VALUE x)
{
return DBL2NUM(cos(Get_Double(x)));
}
/*
* call-seq:
* Math.sin(x) -> Float
*
* Computes the sine of +x+ (expressed in radians).
* Returns a Float in the range -1.0..1.0.
*
* Domain: (-INFINITY, INFINITY)
*
* Codomain: [-1, 1]
*
* Math.sin(Math::PI/2) #=> 1.0
*
*/
static VALUE
math_sin(VALUE unused_obj, VALUE x)
{
return DBL2NUM(sin(Get_Double(x)));
}
/*
* call-seq:
* Math.tan(x) -> Float
*
* Computes the tangent of +x+ (expressed in radians).
*
* Domain: (-INFINITY, INFINITY)
*
* Codomain: (-INFINITY, INFINITY)
*
* Math.tan(0) #=> 0.0
*
*/
static VALUE
math_tan(VALUE unused_obj, VALUE x)
{
return DBL2NUM(tan(Get_Double(x)));
}
/*
* call-seq:
* Math.acos(x) -> Float
*
* Computes the arc cosine of +x+. Returns 0..PI.
*
* Domain: [-1, 1]
*
* Codomain: [0, PI]
*
* Math.acos(0) == Math::PI/2 #=> true
*
*/
static VALUE
math_acos(VALUE unused_obj, VALUE x)
{
double d;
d = Get_Double(x);
/* check for domain error */
if (d < -1.0 || 1.0 < d) domain_error("acos");
return DBL2NUM(acos(d));
}
/*
* call-seq:
* Math.asin(x) -> Float
*
* Computes the arc sine of +x+. Returns -PI/2..PI/2.
*
* Domain: [-1, -1]
*
* Codomain: [-PI/2, PI/2]
*
* Math.asin(1) == Math::PI/2 #=> true
*/
static VALUE
math_asin(VALUE unused_obj, VALUE x)
{
double d;
d = Get_Double(x);
/* check for domain error */
if (d < -1.0 || 1.0 < d) domain_error("asin");
return DBL2NUM(asin(d));
}
/*
* call-seq:
* Math.atan(x) -> Float
*
* Computes the arc tangent of +x+. Returns -PI/2..PI/2.
*
* Domain: (-INFINITY, INFINITY)
*
* Codomain: (-PI/2, PI/2)
*
* Math.atan(0) #=> 0.0
*/
static VALUE
math_atan(VALUE unused_obj, VALUE x)
{
return DBL2NUM(atan(Get_Double(x)));
}
#ifndef HAVE_COSH
double
cosh(double x)
{
return (exp(x) + exp(-x)) / 2;
}
#endif
/*
* call-seq:
* Math.cosh(x) -> Float
*
* Computes the hyperbolic cosine of +x+ (expressed in radians).
*
* Domain: (-INFINITY, INFINITY)
*
* Codomain: [1, INFINITY)
*
* Math.cosh(0) #=> 1.0
*
*/
static VALUE
math_cosh(VALUE unused_obj, VALUE x)
{
return DBL2NUM(cosh(Get_Double(x)));
}
#ifndef HAVE_SINH
double
sinh(double x)
{
return (exp(x) - exp(-x)) / 2;
}
#endif
/*
* call-seq:
* Math.sinh(x) -> Float
*
* Computes the hyperbolic sine of +x+ (expressed in radians).
*
* Domain: (-INFINITY, INFINITY)
*
* Codomain: (-INFINITY, INFINITY)
*
* Math.sinh(0) #=> 0.0
*
*/
static VALUE
math_sinh(VALUE unused_obj, VALUE x)
{
return DBL2NUM(sinh(Get_Double(x)));
}
#ifndef HAVE_TANH
double
tanh(double x)
{
# if defined(HAVE_SINH) && defined(HAVE_COSH)
const double c = cosh(x);
if (!isinf(c)) return sinh(x) / c;
# else
const double e = exp(x+x);
if (!isinf(e)) return (e - 1) / (e + 1);
# endif
return x > 0 ? 1.0 : -1.0;
}
#endif
/*
* call-seq:
* Math.tanh(x) -> Float
*
* Computes the hyperbolic tangent of +x+ (expressed in radians).
*
* Domain: (-INFINITY, INFINITY)
*
* Codomain: (-1, 1)
*
* Math.tanh(0) #=> 0.0
*
*/
static VALUE
math_tanh(VALUE unused_obj, VALUE x)
{
return DBL2NUM(tanh(Get_Double(x)));
}
/*
* call-seq:
* Math.acosh(x) -> Float
*
* Computes the inverse hyperbolic cosine of +x+.
*
* Domain: [1, INFINITY)
*
* Codomain: [0, INFINITY)
*
* Math.acosh(1) #=> 0.0
*
*/
static VALUE
math_acosh(VALUE unused_obj, VALUE x)
{
double d;
d = Get_Double(x);
/* check for domain error */
if (d < 1.0) domain_error("acosh");
return DBL2NUM(acosh(d));
}
/*
* call-seq:
* Math.asinh(x) -> Float
*
* Computes the inverse hyperbolic sine of +x+.
*
* Domain: (-INFINITY, INFINITY)
*
* Codomain: (-INFINITY, INFINITY)
*
* Math.asinh(1) #=> 0.881373587019543
*
*/
static VALUE
math_asinh(VALUE unused_obj, VALUE x)
{
return DBL2NUM(asinh(Get_Double(x)));
}
/*
* call-seq:
* Math.atanh(x) -> Float
*
* Computes the inverse hyperbolic tangent of +x+.
*
* Domain: (-1, 1)
*
* Codomain: (-INFINITY, INFINITY)
*
* Math.atanh(1) #=> Infinity
*
*/
static VALUE
math_atanh(VALUE unused_obj, VALUE x)
{
double d;
d = Get_Double(x);
/* check for domain error */
if (d < -1.0 || +1.0 < d) domain_error("atanh");
/* check for pole error */
if (d == -1.0) return DBL2NUM(-INFINITY);
if (d == +1.0) return DBL2NUM(+INFINITY);
return DBL2NUM(atanh(d));
}
/*
* call-seq:
* Math.exp(x) -> Float
*
* Returns e**x.
*
* Domain: (-INFINITY, INFINITY)
*
* Codomain: (0, INFINITY)
*
* Math.exp(0) #=> 1.0
* Math.exp(1) #=> 2.718281828459045
* Math.exp(1.5) #=> 4.4816890703380645
*
*/
static VALUE
math_exp(VALUE unused_obj, VALUE x)
{
return DBL2NUM(exp(Get_Double(x)));
}
#if defined __CYGWIN__
# include <cygwin/version.h>
# if CYGWIN_VERSION_DLL_MAJOR < 1005
# define nan(x) nan()
# endif
# define log(x) ((x) < 0.0 ? nan("") : log(x))
# define log10(x) ((x) < 0.0 ? nan("") : log10(x))
#endif
#ifndef M_LN2
# define M_LN2 0.693147180559945309417232121458176568
#endif
#ifndef M_LN10
# define M_LN10 2.30258509299404568401799145468436421
#endif
static double math_log1(VALUE x);
/*
* call-seq:
* Math.log(x) -> Float
* Math.log(x, base) -> Float
*
* Returns the logarithm of +x+.
* If additional second argument is given, it will be the base
* of logarithm. Otherwise it is +e+ (for the natural logarithm).
*
* Domain: (0, INFINITY)
*
* Codomain: (-INFINITY, INFINITY)
*
* Math.log(0) #=> -Infinity
* Math.log(1) #=> 0.0
* Math.log(Math::E) #=> 1.0
* Math.log(Math::E**3) #=> 3.0
* Math.log(12, 3) #=> 2.2618595071429146
*
*/
static VALUE
math_log(int argc, const VALUE *argv, VALUE unused_obj)
{
VALUE x, base;
double d;
rb_scan_args(argc, argv, "11", &x, &base);
d = math_log1(x);
if (argc == 2) {
d /= math_log1(base);
}
return DBL2NUM(d);
}
static double
get_double_rshift(VALUE x, size_t *pnumbits)
{
size_t numbits;
if (RB_BIGNUM_TYPE_P(x) && BIGNUM_POSITIVE_P(x) &&
DBL_MAX_EXP <= (numbits = rb_absint_numwords(x, 1, NULL))) {
numbits -= DBL_MANT_DIG;
x = rb_big_rshift(x, SIZET2NUM(numbits));
}
else {
numbits = 0;
}
*pnumbits = numbits;
return Get_Double(x);
}
static double
math_log1(VALUE x)
{
size_t numbits;
double d = get_double_rshift(x, &numbits);
/* check for domain error */
if (d < 0.0) domain_error("log");
/* check for pole error */
if (d == 0.0) return -INFINITY;
return log(d) + numbits * M_LN2; /* log(d * 2 ** numbits) */
}
#ifndef log2
#ifndef HAVE_LOG2
double
log2(double x)
{
return log10(x)/log10(2.0);
}
#else
extern double log2(double);
#endif
#endif
/*
* call-seq:
* Math.log2(x) -> Float
*
* Returns the base 2 logarithm of +x+.
*
* Domain: (0, INFINITY)
*
* Codomain: (-INFINITY, INFINITY)
*
* Math.log2(1) #=> 0.0
* Math.log2(2) #=> 1.0
* Math.log2(32768) #=> 15.0
* Math.log2(65536) #=> 16.0
*
*/
static VALUE
math_log2(VALUE unused_obj, VALUE x)
{
size_t numbits;
double d = get_double_rshift(x, &numbits);
/* check for domain error */
if (d < 0.0) domain_error("log2");
/* check for pole error */
if (d == 0.0) return DBL2NUM(-INFINITY);
return DBL2NUM(log2(d) + numbits); /* log2(d * 2 ** numbits) */
}
/*
* call-seq:
* Math.log10(x) -> Float
*
* Returns the base 10 logarithm of +x+.
*
* Domain: (0, INFINITY)
*
* Codomain: (-INFINITY, INFINITY)
*
* Math.log10(1) #=> 0.0
* Math.log10(10) #=> 1.0
* Math.log10(10**100) #=> 100.0
*
*/
static VALUE
math_log10(VALUE unused_obj, VALUE x)
{
size_t numbits;
double d = get_double_rshift(x, &numbits);
/* check for domain error */
if (d < 0.0) domain_error("log10");
/* check for pole error */
if (d == 0.0) return DBL2NUM(-INFINITY);
return DBL2NUM(log10(d) + numbits * log10(2)); /* log10(d * 2 ** numbits) */
}
/*
* call-seq:
* Math.sqrt(x) -> Float
*
* Returns the non-negative square root of +x+.
*
* Domain: [0, INFINITY)
*
* Codomain:[0, INFINITY)
*
* 0.upto(10) {|x|
* p [x, Math.sqrt(x), Math.sqrt(x)**2]
* }
* #=> [0, 0.0, 0.0]
* # [1, 1.0, 1.0]
* # [2, 1.4142135623731, 2.0]
* # [3, 1.73205080756888, 3.0]
* # [4, 2.0, 4.0]
* # [5, 2.23606797749979, 5.0]
* # [6, 2.44948974278318, 6.0]
* # [7, 2.64575131106459, 7.0]
* # [8, 2.82842712474619, 8.0]
* # [9, 3.0, 9.0]
* # [10, 3.16227766016838, 10.0]
*
* Note that the limited precision of floating point arithmetic
* might lead to surprising results:
*
* Math.sqrt(10**46).to_i #=> 99999999999999991611392 (!)
*
* See also BigDecimal#sqrt.
*/
static VALUE
math_sqrt(VALUE unused_obj, VALUE x)
{
return rb_math_sqrt(x);
}
#define f_boolcast(x) ((x) ? Qtrue : Qfalse)
inline static VALUE
f_negative_p(VALUE x)
{
if (FIXNUM_P(x))
return f_boolcast(FIX2LONG(x) < 0);
return rb_funcall(x, '<', 1, INT2FIX(0));
}
inline static VALUE
f_signbit(VALUE x)
{
if (RB_TYPE_P(x, T_FLOAT)) {
double f = RFLOAT_VALUE(x);
return f_boolcast(!isnan(f) && signbit(f));
}
return f_negative_p(x);
}
VALUE
rb_math_sqrt(VALUE x)
{
double d;
if (RB_TYPE_P(x, T_COMPLEX)) {
VALUE neg = f_signbit(RCOMPLEX(x)->imag);
double re = Get_Double(RCOMPLEX(x)->real), im;
d = Get_Double(rb_complex_abs(x));
im = sqrt((d - re) / 2.0);
re = sqrt((d + re) / 2.0);
if (neg) im = -im;
return rb_complex_new(DBL2NUM(re), DBL2NUM(im));
}
d = Get_Double(x);
/* check for domain error */
if (d < 0.0) domain_error("sqrt");
if (d == 0.0) return DBL2NUM(0.0);
return DBL2NUM(sqrt(d));
}
/*
* call-seq:
* Math.cbrt(x) -> Float
*
* Returns the cube root of +x+.
*
* Domain: (-INFINITY, INFINITY)
*
* Codomain: (-INFINITY, INFINITY)
*
* -9.upto(9) {|x|
* p [x, Math.cbrt(x), Math.cbrt(x)**3]
* }
* #=> [-9, -2.0800838230519, -9.0]
* # [-8, -2.0, -8.0]
* # [-7, -1.91293118277239, -7.0]
* # [-6, -1.81712059283214, -6.0]
* # [-5, -1.7099759466767, -5.0]
* # [-4, -1.5874010519682, -4.0]
* # [-3, -1.44224957030741, -3.0]
* # [-2, -1.25992104989487, -2.0]
* # [-1, -1.0, -1.0]
* # [0, 0.0, 0.0]
* # [1, 1.0, 1.0]
* # [2, 1.25992104989487, 2.0]
* # [3, 1.44224957030741, 3.0]
* # [4, 1.5874010519682, 4.0]
* # [5, 1.7099759466767, 5.0]
* # [6, 1.81712059283214, 6.0]
* # [7, 1.91293118277239, 7.0]
* # [8, 2.0, 8.0]
* # [9, 2.0800838230519, 9.0]
*
*/
static VALUE
math_cbrt(VALUE unused_obj, VALUE x)
{
return DBL2NUM(cbrt(Get_Double(x)));
}
/*
* call-seq:
* Math.frexp(x) -> [fraction, exponent]
*
* Returns a two-element array containing the normalized fraction (a Float)
* and exponent (an Integer) of +x+.
*
* fraction, exponent = Math.frexp(1234) #=> [0.6025390625, 11]
* fraction * 2**exponent #=> 1234.0
*/
static VALUE
math_frexp(VALUE unused_obj, VALUE x)
{
double d;
int exp;
d = frexp(Get_Double(x), &exp);
return rb_assoc_new(DBL2NUM(d), INT2NUM(exp));
}
/*
* call-seq:
* Math.ldexp(fraction, exponent) -> float
*
* Returns the value of +fraction+*(2**+exponent+).
*
* fraction, exponent = Math.frexp(1234)
* Math.ldexp(fraction, exponent) #=> 1234.0
*/
static VALUE
math_ldexp(VALUE unused_obj, VALUE x, VALUE n)
{
return DBL2NUM(ldexp(Get_Double(x), NUM2INT(n)));
}
/*
* call-seq:
* Math.hypot(x, y) -> Float
*
* Returns sqrt(x**2 + y**2), the hypotenuse of a right-angled triangle with
* sides +x+ and +y+.
*
* Math.hypot(3, 4) #=> 5.0
*/
static VALUE
math_hypot(VALUE unused_obj, VALUE x, VALUE y)
{
return DBL2NUM(hypot(Get_Double(x), Get_Double(y)));
}
/*
* call-seq:
* Math.erf(x) -> Float
*
* Calculates the error function of +x+.
*
* Domain: (-INFINITY, INFINITY)
*
* Codomain: (-1, 1)
*
* Math.erf(0) #=> 0.0
*
*/
static VALUE
math_erf(VALUE unused_obj, VALUE x)
{
return DBL2NUM(erf(Get_Double(x)));
}
/*
* call-seq:
* Math.erfc(x) -> Float
*
* Calculates the complementary error function of x.
*
* Domain: (-INFINITY, INFINITY)
*
* Codomain: (0, 2)
*
* Math.erfc(0) #=> 1.0
*
*/
static VALUE
math_erfc(VALUE unused_obj, VALUE x)
{
return DBL2NUM(erfc(Get_Double(x)));
}
#if defined __MINGW32__
static inline double
ruby_tgamma(const double d)
{
const double g = tgamma(d);
if (isinf(g)) {
if (d == 0.0 && signbit(d)) return -INFINITY;
}
if (isnan(g)) {
if (!signbit(d)) return INFINITY;
}
return g;
}
#define tgamma(d) ruby_tgamma(d)
#endif
#if defined LGAMMA_R_PM0_FIX
static inline double
ruby_lgamma_r(const double d, int *sign)
{
const double g = lgamma_r(d, sign);
if (isinf(g)) {
if (d == 0.0 && signbit(d)) {
*sign = -1;
return INFINITY;
} else if (d == 0.0 && !signbit(d)) {
*sign = 1;
return INFINITY;
}
}
return g;
}
#define lgamma_r(d, sign) ruby_lgamma_r(d, sign)
#endif
/*
* call-seq:
* Math.gamma(x) -> Float
*
* Calculates the gamma function of x.
*
* Note that gamma(n) is same as fact(n-1) for integer n > 0.
* However gamma(n) returns float and can be an approximation.
*
* def fact(n) (1..n).inject(1) {|r,i| r*i } end
* 1.upto(26) {|i| p [i, Math.gamma(i), fact(i-1)] }
* #=> [1, 1.0, 1]
* # [2, 1.0, 1]
* # [3, 2.0, 2]
* # [4, 6.0, 6]
* # [5, 24.0, 24]
* # [6, 120.0, 120]
* # [7, 720.0, 720]
* # [8, 5040.0, 5040]
* # [9, 40320.0, 40320]
* # [10, 362880.0, 362880]
* # [11, 3628800.0, 3628800]
* # [12, 39916800.0, 39916800]
* # [13, 479001600.0, 479001600]
* # [14, 6227020800.0, 6227020800]
* # [15, 87178291200.0, 87178291200]
* # [16, 1307674368000.0, 1307674368000]
* # [17, 20922789888000.0, 20922789888000]
* # [18, 355687428096000.0, 355687428096000]
* # [19, 6.402373705728e+15, 6402373705728000]
* # [20, 1.21645100408832e+17, 121645100408832000]
* # [21, 2.43290200817664e+18, 2432902008176640000]
* # [22, 5.109094217170944e+19, 51090942171709440000]
* # [23, 1.1240007277776077e+21, 1124000727777607680000]
* # [24, 2.5852016738885062e+22, 25852016738884976640000]
* # [25, 6.204484017332391e+23, 620448401733239439360000]
* # [26, 1.5511210043330954e+25, 15511210043330985984000000]
*
*/
static VALUE
math_gamma(VALUE unused_obj, VALUE x)
{
static const double fact_table[] = {
/* fact(0) */ 1.0,
/* fact(1) */ 1.0,
/* fact(2) */ 2.0,
/* fact(3) */ 6.0,
/* fact(4) */ 24.0,
/* fact(5) */ 120.0,
/* fact(6) */ 720.0,
/* fact(7) */ 5040.0,
/* fact(8) */ 40320.0,
/* fact(9) */ 362880.0,
/* fact(10) */ 3628800.0,
/* fact(11) */ 39916800.0,
/* fact(12) */ 479001600.0,
/* fact(13) */ 6227020800.0,
/* fact(14) */ 87178291200.0,
/* fact(15) */ 1307674368000.0,
/* fact(16) */ 20922789888000.0,
/* fact(17) */ 355687428096000.0,
/* fact(18) */ 6402373705728000.0,
/* fact(19) */ 121645100408832000.0,
/* fact(20) */ 2432902008176640000.0,
/* fact(21) */ 51090942171709440000.0,
/* fact(22) */ 1124000727777607680000.0,
/* fact(23)=25852016738884976640000 needs 56bit mantissa which is
* impossible to represent exactly in IEEE 754 double which have
* 53bit mantissa. */
};
enum {NFACT_TABLE = numberof(fact_table)};
double d;
d = Get_Double(x);
/* check for domain error */
if (isinf(d) && signbit(d)) domain_error("gamma");
if (d == floor(d)) {
if (d < 0.0) domain_error("gamma");
if (1.0 <= d && d <= (double)NFACT_TABLE) {
return DBL2NUM(fact_table[(int)d - 1]);
}
}
return DBL2NUM(tgamma(d));
}
/*
* call-seq:
* Math.lgamma(x) -> [float, -1 or 1]
*
* Calculates the logarithmic gamma of +x+ and the sign of gamma of +x+.
*
* Math.lgamma(x) is same as
* [Math.log(Math.gamma(x).abs), Math.gamma(x) < 0 ? -1 : 1]
* but avoid overflow by Math.gamma(x) for large x.
*
* Math.lgamma(0) #=> [Infinity, 1]
*
*/
static VALUE
math_lgamma(VALUE unused_obj, VALUE x)
{
double d;
int sign=1;
VALUE v;
d = Get_Double(x);
/* check for domain error */
if (isinf(d)) {
if (signbit(d)) domain_error("lgamma");
return rb_assoc_new(DBL2NUM(INFINITY), INT2FIX(1));
}
v = DBL2NUM(lgamma_r(d, &sign));
return rb_assoc_new(v, INT2FIX(sign));
}
#define exp1(n) \
VALUE \
rb_math_##n(VALUE x)\
{\
return math_##n(0, x);\
}
#define exp2(n) \
VALUE \
rb_math_##n(VALUE x, VALUE y)\
{\
return math_##n(0, x, y);\
}
exp2(atan2)
exp1(cos)
exp1(cosh)
exp1(exp)
exp2(hypot)
VALUE
rb_math_log(int argc, const VALUE *argv)
{
return math_log(argc, argv, 0);
}
exp1(sin)
exp1(sinh)
#if 0
exp1(sqrt)
#endif
/*
* Document-class: Math::DomainError
*
* Raised when a mathematical function is evaluated outside of its
* domain of definition.
*
* For example, since +cos+ returns values in the range -1..1,
* its inverse function +acos+ is only defined on that interval:
*
* Math.acos(42)
*
* <em>produces:</em>
*
* Math::DomainError: Numerical argument is out of domain - "acos"
*/
/*
* Document-class: Math
*
* The Math module contains module functions for basic
* trigonometric and transcendental functions. See class
* Float for a list of constants that
* define Ruby's floating point accuracy.
*
* Domains and codomains are given only for real (not complex) numbers.
*/
void
InitVM_Math(void)
{
rb_mMath = rb_define_module("Math");
rb_eMathDomainError = rb_define_class_under(rb_mMath, "DomainError", rb_eStandardError);
/* Definition of the mathematical constant PI as a Float number. */
rb_define_const(rb_mMath, "PI", DBL2NUM(M_PI));
#ifdef M_E
/* Definition of the mathematical constant E (e) as a Float number. */
rb_define_const(rb_mMath, "E", DBL2NUM(M_E));
#else
rb_define_const(rb_mMath, "E", DBL2NUM(exp(1.0)));
#endif
rb_define_module_function(rb_mMath, "atan2", math_atan2, 2);
rb_define_module_function(rb_mMath, "cos", math_cos, 1);
rb_define_module_function(rb_mMath, "sin", math_sin, 1);
rb_define_module_function(rb_mMath, "tan", math_tan, 1);
rb_define_module_function(rb_mMath, "acos", math_acos, 1);
rb_define_module_function(rb_mMath, "asin", math_asin, 1);
rb_define_module_function(rb_mMath, "atan", math_atan, 1);
rb_define_module_function(rb_mMath, "cosh", math_cosh, 1);
rb_define_module_function(rb_mMath, "sinh", math_sinh, 1);
rb_define_module_function(rb_mMath, "tanh", math_tanh, 1);
rb_define_module_function(rb_mMath, "acosh", math_acosh, 1);
rb_define_module_function(rb_mMath, "asinh", math_asinh, 1);
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, "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, "sqrt", math_sqrt, 1);
rb_define_module_function(rb_mMath, "cbrt", math_cbrt, 1);
rb_define_module_function(rb_mMath, "frexp", math_frexp, 1);
rb_define_module_function(rb_mMath, "ldexp", math_ldexp, 2);
rb_define_module_function(rb_mMath, "hypot", math_hypot, 2);
rb_define_module_function(rb_mMath, "erf", math_erf, 1);
rb_define_module_function(rb_mMath, "erfc", math_erfc, 1);
rb_define_module_function(rb_mMath, "gamma", math_gamma, 1);
rb_define_module_function(rb_mMath, "lgamma", math_lgamma, 1);
}
void
Init_Math(void)
{
InitVM(Math);
}
View git blame Copy permalink