summaryrefslogtreecommitdiff
path: root/libm/float/gdtrf.c
diff options
context:
space:
mode:
authorEric Andersen <andersen@codepoet.org>2001-05-10 00:40:28 +0000
committerEric Andersen <andersen@codepoet.org>2001-05-10 00:40:28 +0000
commit1077fa4d772832f77a677ce7fb7c2d513b959e3f (patch)
tree579bee13fb0b58d2800206366ec2caecbb15f3fc /libm/float/gdtrf.c
parent22358dd7ce7bb49792204b698f01a6f69b9c8e08 (diff)
uClibc now has a math library. muahahahaha!
-Erik
Diffstat (limited to 'libm/float/gdtrf.c')
-rw-r--r--libm/float/gdtrf.c144
1 files changed, 144 insertions, 0 deletions
diff --git a/libm/float/gdtrf.c b/libm/float/gdtrf.c
new file mode 100644
index 000000000..e7e02026b
--- /dev/null
+++ b/libm/float/gdtrf.c
@@ -0,0 +1,144 @@
+/* gdtrf.c
+ *
+ * Gamma distribution function
+ *
+ *
+ *
+ * SYNOPSIS:
+ *
+ * float a, b, x, y, gdtrf();
+ *
+ * y = gdtrf( a, b, x );
+ *
+ *
+ *
+ * DESCRIPTION:
+ *
+ * Returns the integral from zero to x of the gamma probability
+ * density function:
+ *
+ *
+ * x
+ * b -
+ * a | | b-1 -at
+ * y = ----- | t e dt
+ * - | |
+ * | (b) -
+ * 0
+ *
+ * The incomplete gamma integral is used, according to the
+ * relation
+ *
+ * y = igam( b, ax ).
+ *
+ *
+ * ACCURACY:
+ *
+ * Relative error:
+ * arithmetic domain # trials peak rms
+ * IEEE 0,100 5000 5.8e-5 3.0e-6
+ *
+ * ERROR MESSAGES:
+ *
+ * message condition value returned
+ * gdtrf domain x < 0 0.0
+ *
+ */
+ /* gdtrcf.c
+ *
+ * Complemented gamma distribution function
+ *
+ *
+ *
+ * SYNOPSIS:
+ *
+ * float a, b, x, y, gdtrcf();
+ *
+ * y = gdtrcf( a, b, x );
+ *
+ *
+ *
+ * DESCRIPTION:
+ *
+ * Returns the integral from x to infinity of the gamma
+ * probability density function:
+ *
+ *
+ * inf.
+ * b -
+ * a | | b-1 -at
+ * y = ----- | t e dt
+ * - | |
+ * | (b) -
+ * x
+ *
+ * The incomplete gamma integral is used, according to the
+ * relation
+ *
+ * y = igamc( b, ax ).
+ *
+ *
+ * ACCURACY:
+ *
+ * Relative error:
+ * arithmetic domain # trials peak rms
+ * IEEE 0,100 5000 9.1e-5 1.5e-5
+ *
+ * ERROR MESSAGES:
+ *
+ * message condition value returned
+ * gdtrcf domain x < 0 0.0
+ *
+ */
+
+/* gdtr() */
+
+
+/*
+Cephes Math Library Release 2.2: July, 1992
+Copyright 1984, 1987, 1992 by Stephen L. Moshier
+Direct inquiries to 30 Frost Street, Cambridge, MA 02140
+*/
+
+#include <math.h>
+#ifdef ANSIC
+float igamf(float, float), igamcf(float, float);
+#else
+float igamf(), igamcf();
+#endif
+
+
+
+float gdtrf( float aa, float bb, float xx )
+{
+float a, b, x;
+
+a = aa;
+b = bb;
+x = xx;
+
+
+if( x < 0.0 )
+ {
+ mtherr( "gdtrf", DOMAIN );
+ return( 0.0 );
+ }
+return( igamf( b, a * x ) );
+}
+
+
+
+float gdtrcf( float aa, float bb, float xx )
+{
+float a, b, x;
+
+a = aa;
+b = bb;
+x = xx;
+if( x < 0.0 )
+ {
+ mtherr( "gdtrcf", DOMAIN );
+ return( 0.0 );
+ }
+return( igamcf( b, a * x ) );
+}