From 7ce331c01ce6eb7b3f5c715a38a24359da9c6ee2 Mon Sep 17 00:00:00 2001
From: Eric Andersen <andersen@codepoet.org>
Date: Thu, 22 Nov 2001 14:04:29 +0000
Subject: Totally rework the math library, this time based on the MacOs X math
 library (which is itself based on the math lib from FreeBSD).  -Erik

---
 libm/double/igam.c | 210 -----------------------------------------------------
 1 file changed, 210 deletions(-)
 delete mode 100644 libm/double/igam.c

(limited to 'libm/double/igam.c')

diff --git a/libm/double/igam.c b/libm/double/igam.c
deleted file mode 100644
index a1d0bab36..000000000
--- a/libm/double/igam.c
+++ /dev/null
@@ -1,210 +0,0 @@
-/*							igam.c
- *
- *	Incomplete gamma integral
- *
- *
- *
- * SYNOPSIS:
- *
- * double a, x, y, igam();
- *
- * y = igam( a, x );
- *
- * DESCRIPTION:
- *
- * The function is defined by
- *
- *                           x
- *                            -
- *                   1       | |  -t  a-1
- *  igam(a,x)  =   -----     |   e   t   dt.
- *                  -      | |
- *                 | (a)    -
- *                           0
- *
- *
- * In this implementation both arguments must be positive.
- * The integral is evaluated by either a power series or
- * continued fraction expansion, depending on the relative
- * values of a and x.
- *
- * ACCURACY:
- *
- *                      Relative error:
- * arithmetic   domain     # trials      peak         rms
- *    IEEE      0,30       200000       3.6e-14     2.9e-15
- *    IEEE      0,100      300000       9.9e-14     1.5e-14
- */
-/*							igamc()
- *
- *	Complemented incomplete gamma integral
- *
- *
- *
- * SYNOPSIS:
- *
- * double a, x, y, igamc();
- *
- * y = igamc( a, x );
- *
- * DESCRIPTION:
- *
- * The function is defined by
- *
- *
- *  igamc(a,x)   =   1 - igam(a,x)
- *
- *                            inf.
- *                              -
- *                     1       | |  -t  a-1
- *               =   -----     |   e   t   dt.
- *                    -      | |
- *                   | (a)    -
- *                             x
- *
- *
- * In this implementation both arguments must be positive.
- * The integral is evaluated by either a power series or
- * continued fraction expansion, depending on the relative
- * values of a and x.
- *
- * ACCURACY:
- *
- * Tested at random a, x.
- *                a         x                      Relative error:
- * arithmetic   domain   domain     # trials      peak         rms
- *    IEEE     0.5,100   0,100      200000       1.9e-14     1.7e-15
- *    IEEE     0.01,0.5  0,100      200000       1.4e-13     1.6e-15
- */
-
-/*
-Cephes Math Library Release 2.8:  June, 2000
-Copyright 1985, 1987, 2000 by Stephen L. Moshier
-*/
-
-#include <math.h>
-#ifdef ANSIPROT
-extern double lgam ( double );
-extern double exp ( double );
-extern double log ( double );
-extern double fabs ( double );
-extern double igam ( double, double );
-extern double igamc ( double, double );
-#else
-double lgam(), exp(), log(), fabs(), igam(), igamc();
-#endif
-
-extern double MACHEP, MAXLOG;
-static double big = 4.503599627370496e15;
-static double biginv =  2.22044604925031308085e-16;
-
-double igamc( a, x )
-double a, x;
-{
-double ans, ax, c, yc, r, t, y, z;
-double pk, pkm1, pkm2, qk, qkm1, qkm2;
-
-if( (x <= 0) || ( a <= 0) )
-	return( 1.0 );
-
-if( (x < 1.0) || (x < a) )
-	return( 1.0 - igam(a,x) );
-
-ax = a * log(x) - x - lgam(a);
-if( ax < -MAXLOG )
-	{
-	mtherr( "igamc", UNDERFLOW );
-	return( 0.0 );
-	}
-ax = exp(ax);
-
-/* continued fraction */
-y = 1.0 - a;
-z = x + y + 1.0;
-c = 0.0;
-pkm2 = 1.0;
-qkm2 = x;
-pkm1 = x + 1.0;
-qkm1 = z * x;
-ans = pkm1/qkm1;
-
-do
-	{
-	c += 1.0;
-	y += 1.0;
-	z += 2.0;
-	yc = y * c;
-	pk = pkm1 * z  -  pkm2 * yc;
-	qk = qkm1 * z  -  qkm2 * yc;
-	if( qk != 0 )
-		{
-		r = pk/qk;
-		t = fabs( (ans - r)/r );
-		ans = r;
-		}
-	else
-		t = 1.0;
-	pkm2 = pkm1;
-	pkm1 = pk;
-	qkm2 = qkm1;
-	qkm1 = qk;
-	if( fabs(pk) > big )
-		{
-		pkm2 *= biginv;
-		pkm1 *= biginv;
-		qkm2 *= biginv;
-		qkm1 *= biginv;
-		}
-	}
-while( t > MACHEP );
-
-return( ans * ax );
-}
-
-
-
-/* left tail of incomplete gamma function:
- *
- *          inf.      k
- *   a  -x   -       x
- *  x  e     >   ----------
- *           -     -
- *          k=0   | (a+k+1)
- *
- */
-
-double igam( a, x )
-double a, x;
-{
-double ans, ax, c, r;
-
-if( (x <= 0) || ( a <= 0) )
-	return( 0.0 );
-
-if( (x > 1.0) && (x > a ) )
-	return( 1.0 - igamc(a,x) );
-
-/* Compute  x**a * exp(-x) / gamma(a)  */
-ax = a * log(x) - x - lgam(a);
-if( ax < -MAXLOG )
-	{
-	mtherr( "igam", UNDERFLOW );
-	return( 0.0 );
-	}
-ax = exp(ax);
-
-/* power series */
-r = a;
-c = 1.0;
-ans = 1.0;
-
-do
-	{
-	r += 1.0;
-	c *= x/r;
-	ans += c;
-	}
-while( c/ans > MACHEP );
-
-return( ans * ax/a );
-}
-- 
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