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authorakr <akr@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>2008-02-07 01:43:43 (GMT)
committerakr <akr@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>2008-02-07 01:43:43 (GMT)
commit14373fc4db7440d39db4fd39297f2ed44cc990f2 (patch)
tree966d984fadcafb2d9046a161b1e170d99904a592
parentb88ecbcffc30fdf8b5743003563e10a347c05b03 (diff)
* 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. git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@15388 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
-rw-r--r--ChangeLog21
-rw-r--r--LEGAL2
-rw-r--r--configure.in3
-rw-r--r--include/ruby/missing.h8
-rw-r--r--math.c73
-rw-r--r--missing/lgamma_r.c64
-rw-r--r--missing/tgamma.c49
7 files changed, 219 insertions, 1 deletions
diff --git a/ChangeLog b/ChangeLog
index 76c095e..5334801 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -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
diff --git a/LEGAL b/LEGAL
index b12bf66..51dfb22 100644
--- a/LEGAL
+++ b/LEGAL
@@ -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:
diff --git a/configure.in b/configure.in
index d490f87..28e85f3 100644
--- a/configure.in
+++ b/configure.in
@@ -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\
diff --git a/include/ruby/missing.h b/include/ruby/missing.h
index da38a3e..cfa430d 100644
--- a/include/ruby/missing.h
+++ b/include/ruby/missing.h
@@ -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)
diff --git a/math.c b/math.c
index 332d899..3a4ed73 100644
--- a/math.c
+++ b/math.c
@@ -487,6 +487,76 @@ math_erfc(VALUE obj, 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
* <code>Float</code> for a list of constants that
@@ -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);
}
diff --git a/missing/lgamma_r.c b/missing/lgamma_r.c
new file mode 100644
index 0000000..70b6259
--- /dev/null
+++ b/missing/lgamma_r.c
@@ -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);
+}
diff --git a/missing/tgamma.c b/missing/tgamma.c
new file mode 100644
index 0000000..a30108e
--- /dev/null
+++ b/missing/tgamma.c
@@ -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));
+}
+