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* math.c (math_gamma): new method Math.gamma.

Browse source 
(math_lgamma): new method Math.lgamma.

* include/ruby/missing.h (tgamma): declared unless HAVE_TGAMMA.
  (lgamma_r): declared unless HAVE_LGAMMA_R.

* configure.in (tgamma): check for replacement funtions.
  (lgamma_r): ditto.

* missing/tgamma.c: new file.  based on gamma.c from
  "C-gengo niyoru saishin algorithm jiten" (New Algorithm handbook
  in C language) (Gijyutsu hyouron sha, Tokyo, 1991)
  by Haruhiko Okumura.

* missing/lgamma_r.c: ditto.

* LEGAL (missing/tgamma.c): describe as public domain.
  (missing/lgamma_r.c): ditto.



git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@15388 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
This commit is contained in:
akr 2008-02-07 01:43:43 +00:00
parent b88ecbcffc
commit 14373fc4db
7 changed files with 219 additions and 1 deletions
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21
ChangeLog
View file

@ -1,3 +1,24 @@
Thu Feb 7 10:39:21 2008 Tanaka Akira <akr@fsij.org>
* math.c (math_gamma): new method Math.gamma.
(math_lgamma): new method Math.lgamma.
* include/ruby/missing.h (tgamma): declared unless HAVE_TGAMMA.
(lgamma_r): declared unless HAVE_LGAMMA_R.
* configure.in (tgamma): check for replacement funtions.
(lgamma_r): ditto.
* missing/tgamma.c: new file. based on gamma.c from
"C-gengo niyoru saishin algorithm jiten" (New Algorithm handbook
in C language) (Gijyutsu hyouron sha, Tokyo, 1991)
by Haruhiko Okumura.
* missing/lgamma_r.c: ditto.
* LEGAL (missing/tgamma.c): describe as public domain.
(missing/lgamma_r.c): ditto.
Thu Feb 7 09:05:57 2008 Yukihiro Matsumoto <matz@ruby-lang.org>
* ext/nkf/nkf-utf8/nkf.c (nkf_enc_from_index): BINARY does not

2
LEGAL
View file

@ -158,6 +158,8 @@ ext/digest/sha1/sha1.[ch]:
These files are all under public domain.
missing/erf.c:
missing/tgamma.c:
missing/lgamma_r.c:
missing/crypt.c:
missing/vsnprintf.c:

3
configure.in
View file

@ -649,7 +649,8 @@ esac
AC_FUNC_MEMCMP
AC_REPLACE_FUNCS(dup2 memmove strerror strftime\
strchr strstr crypt flock vsnprintf\
isnan finite isinf hypot acosh erf strlcpy strlcat)
isnan finite isinf hypot acosh erf tgamma lgamma_r \
strlcpy strlcat)
AC_CHECK_FUNCS(fmod killpg wait4 waitpid fork spawnv syscall chroot fsync getcwd eaccess\
truncate chsize times utimes utimensat fcntl lockf lstat\
link symlink readlink\

8
include/ruby/missing.h
View file

@ -79,6 +79,14 @@ extern double erf(double);
extern double erfc(double);
#endif
#ifndef HAVE_TGAMMA
extern double tgamma(double);
#endif
#ifndef HAVE_LGAMMA_R
extern double lgamma_r(double, int *);
#endif
#ifndef isinf
# ifndef HAVE_ISINF
# if defined(HAVE_FINITE) && defined(HAVE_ISNAN)

73
math.c
View file

@ -486,6 +486,76 @@ math_erfc(VALUE obj, VALUE x)
return DOUBLE2NUM(erfc(RFLOAT_VALUE(x)));
}
/*
* 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 possibly has error in calculation.
*
* def fact(n) (1..n).inject(1) {|r,i| r*i } end
* 0.upto(25) {|i| p [i, Math.gamma(i+1), fact(i)] }
* =>
* [0, 1.0, 1]
* [1, 1.0, 1]
* [2, 2.0, 2]
* [3, 6.0, 6]
* [4, 24.0, 24]
* [5, 120.0, 120]
* [6, 720.0, 720]
* [7, 5040.0, 5040]
* [8, 40320.0, 40320]
* [9, 362880.0, 362880]
* [10, 3628800.0, 3628800]
* [11, 39916800.0, 39916800]
* [12, 479001599.999999, 479001600]
* [13, 6227020800.00001, 6227020800]
* [14, 87178291199.9998, 87178291200]
* [15, 1307674368000.0, 1307674368000]
* [16, 20922789888000.0, 20922789888000]
* [17, 3.55687428096001e+14, 355687428096000]
* [18, 6.40237370572799e+15, 6402373705728000]
* [19, 1.21645100408832e+17, 121645100408832000]
* [20, 2.43290200817664e+18, 2432902008176640000]
* [21, 5.10909421717094e+19, 51090942171709440000]
* [22, 1.12400072777761e+21, 1124000727777607680000]
* [23, 2.58520167388851e+22, 25852016738884976640000]
* [24, 6.20448401733239e+23, 620448401733239439360000]
* [25, 1.5511210043331e+25, 15511210043330985984000000]
*
*/
static VALUE
math_gamma(VALUE obj, VALUE x)
{
Need_Float(x);
return DOUBLE2NUM(tgamma(RFLOAT_VALUE(x)));
}
/*
* 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)), Math.gamma(x) < 0 ? -1 : 1]
* but avoid overflow by Math.gamma(x) for large x.
*/
static VALUE
math_lgamma(VALUE obj, VALUE x)
{
int sign;
VALUE v;
Need_Float(x);
v = DOUBLE2NUM(lgamma_r(RFLOAT_VALUE(x), &sign));
return rb_assoc_new(v, INT2FIX(sign));
}
/*
* The <code>Math</code> module contains module functions for basic
* trigonometric and transcendental functions. See class
@ -541,4 +611,7 @@ Init_Math(void)
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);
}

64
missing/lgamma_r.c Normal file
View file

@ -0,0 +1,64 @@
/* lgamma_r.c - public domain implementation of error function lgamma_r(3m)
lgamma_r() is based on gamma(). modified by Tanaka Akira.
reference - Haruhiko Okumura: C-gengo niyoru saishin algorithm jiten
(New Algorithm handbook in C language) (Gijyutsu hyouron
sha, Tokyo, 1991) [in Japanese]
http://oku.edu.mie-u.ac.jp/~okumura/algo/
*/
/***********************************************************
gamma.c -- Gamma function
***********************************************************/
#include <math.h>
#define PI 3.14159265358979324 /* $\pi$ */
#define LOG_2PI 1.83787706640934548 /* $\log 2\pi$ */
#define LOG_PI 1.14472988584940017 /* $\log_e \pi$ */
#define N 8
#define B0 1 /* Bernoulli numbers */
#define B1 (-1.0 / 2.0)
#define B2 ( 1.0 / 6.0)
#define B4 (-1.0 / 30.0)
#define B6 ( 1.0 / 42.0)
#define B8 (-1.0 / 30.0)
#define B10 ( 5.0 / 66.0)
#define B12 (-691.0 / 2730.0)
#define B14 ( 7.0 / 6.0)
#define B16 (-3617.0 / 510.0)
static double
loggamma(double x) /* the natural logarithm of the Gamma function. */
{
double v, w;
v = 1;
while (x < N) { v *= x; x++; }
w = 1 / (x * x);
return ((((((((B16 / (16 * 15)) * w + (B14 / (14 * 13))) * w
+ (B12 / (12 * 11))) * w + (B10 / (10 * 9))) * w
+ (B8 / ( 8 * 7))) * w + (B6 / ( 6 * 5))) * w
+ (B4 / ( 4 * 3))) * w + (B2 / ( 2 * 1))) / x
+ 0.5 * LOG_2PI - log(v) - x + (x - 0.5) * log(x);
}
/* the natural logarithm of the absolute value of the Gamma function */
double
lgamma_r(double x, int *signp)
{
if (x < 0) {
double i, f, s;
f = modf(-x, &i);
if (f == 0.0) {
*signp = 1;
return 1.0/0.0;
}
*signp = (fmod(i, 2.0) != 0.0) ? 1 : -1;
s = sin(PI * x);
if (s < 0) s = -s;
return LOG_PI - log(s) - loggamma(1 - x);
}
*signp = 1;
return loggamma(x);
}

49
missing/tgamma.c Normal file
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@ -0,0 +1,49 @@
/* tgamma.c - public domain implementation of error function tgamma(3m)
reference - Haruhiko Okumura: C-gengo niyoru saishin algorithm jiten
(New Algorithm handbook in C language) (Gijyutsu hyouron
sha, Tokyo, 1991) [in Japanese]
http://oku.edu.mie-u.ac.jp/~okumura/algo/
*/
/***********************************************************
gamma.c -- Gamma function
***********************************************************/
#include <math.h>
#define PI 3.14159265358979324 /* $\pi$ */
#define LOG_2PI 1.83787706640934548 /* $\log 2\pi$ */
#define N 8
#define B0 1 /* Bernoulli numbers */
#define B1 (-1.0 / 2.0)
#define B2 ( 1.0 / 6.0)
#define B4 (-1.0 / 30.0)
#define B6 ( 1.0 / 42.0)
#define B8 (-1.0 / 30.0)
#define B10 ( 5.0 / 66.0)
#define B12 (-691.0 / 2730.0)
#define B14 ( 7.0 / 6.0)
#define B16 (-3617.0 / 510.0)
static double
loggamma(double x) /* the natural logarithm of the Gamma function. */
{
double v, w;
v = 1;
while (x < N) { v *= x; x++; }
w = 1 / (x * x);
return ((((((((B16 / (16 * 15)) * w + (B14 / (14 * 13))) * w
+ (B12 / (12 * 11))) * w + (B10 / (10 * 9))) * w
+ (B8 / ( 8 * 7))) * w + (B6 / ( 6 * 5))) * w
+ (B4 / ( 4 * 3))) * w + (B2 / ( 2 * 1))) / x
+ 0.5 * LOG_2PI - log(v) - x + (x - 0.5) * log(x);
}
double tgamma(double x) /* Gamma function */
{
if (x < 0)
return PI / (sin(PI * x) * exp(loggamma(1 - x)));
return exp(loggamma(x));
}