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/igami.c | 187 ----------------------------------------------------
 1 file changed, 187 deletions(-)
 delete mode 100644 libm/double/igami.c

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

diff --git a/libm/double/igami.c b/libm/double/igami.c
deleted file mode 100644
index e93ba2a14..000000000
--- a/libm/double/igami.c
+++ /dev/null
@@ -1,187 +0,0 @@
-/*							igami()
- *
- *      Inverse of complemented imcomplete gamma integral
- *
- *
- *
- * SYNOPSIS:
- *
- * double a, x, p, igami();
- *
- * x = igami( a, p );
- *
- * DESCRIPTION:
- *
- * Given p, the function finds x such that
- *
- *  igamc( a, x ) = p.
- *
- * Starting with the approximate value
- *
- *         3
- *  x = a t
- *
- *  where
- *
- *  t = 1 - d - ndtri(p) sqrt(d)
- * 
- * and
- *
- *  d = 1/9a,
- *
- * the routine performs up to 10 Newton iterations to find the
- * root of igamc(a,x) - p = 0.
- *
- * ACCURACY:
- *
- * Tested at random a, p in the intervals indicated.
- *
- *                a        p                      Relative error:
- * arithmetic   domain   domain     # trials      peak         rms
- *    IEEE     0.5,100   0,0.5       100000       1.0e-14     1.7e-15
- *    IEEE     0.01,0.5  0,0.5       100000       9.0e-14     3.4e-15
- *    IEEE    0.5,10000  0,0.5        20000       2.3e-13     3.8e-14
- */
-
-/*
-Cephes Math Library Release 2.8:  June, 2000
-Copyright 1984, 1987, 1995, 2000 by Stephen L. Moshier
-*/
-
-#include <math.h>
-
-extern double MACHEP, MAXNUM, MAXLOG, MINLOG;
-#ifdef ANSIPROT
-extern double igamc ( double, double );
-extern double ndtri ( double );
-extern double exp ( double );
-extern double fabs ( double );
-extern double log ( double );
-extern double sqrt ( double );
-extern double lgam ( double );
-#else
-double igamc(), ndtri(), exp(), fabs(), log(), sqrt(), lgam();
-#endif
-
-double igami( a, y0 )
-double a, y0;
-{
-double x0, x1, x, yl, yh, y, d, lgm, dithresh;
-int i, dir;
-
-/* bound the solution */
-x0 = MAXNUM;
-yl = 0;
-x1 = 0;
-yh = 1.0;
-dithresh = 5.0 * MACHEP;
-
-/* approximation to inverse function */
-d = 1.0/(9.0*a);
-y = ( 1.0 - d - ndtri(y0) * sqrt(d) );
-x = a * y * y * y;
-
-lgm = lgam(a);
-
-for( i=0; i<10; i++ )
-	{
-	if( x > x0 || x < x1 )
-		goto ihalve;
-	y = igamc(a,x);
-	if( y < yl || y > yh )
-		goto ihalve;
-	if( y < y0 )
-		{
-		x0 = x;
-		yl = y;
-		}
-	else
-		{
-		x1 = x;
-		yh = y;
-		}
-/* compute the derivative of the function at this point */
-	d = (a - 1.0) * log(x) - x - lgm;
-	if( d < -MAXLOG )
-		goto ihalve;
-	d = -exp(d);
-/* compute the step to the next approximation of x */
-	d = (y - y0)/d;
-	if( fabs(d/x) < MACHEP )
-		goto done;
-	x = x - d;
-	}
-
-/* Resort to interval halving if Newton iteration did not converge. */
-ihalve:
-
-d = 0.0625;
-if( x0 == MAXNUM )
-	{
-	if( x <= 0.0 )
-		x = 1.0;
-	while( x0 == MAXNUM )
-		{
-		x = (1.0 + d) * x;
-		y = igamc( a, x );
-		if( y < y0 )
-			{
-			x0 = x;
-			yl = y;
-			break;
-			}
-		d = d + d;
-		}
-	}
-d = 0.5;
-dir = 0;
-
-for( i=0; i<400; i++ )
-	{
-	x = x1  +  d * (x0 - x1);
-	y = igamc( a, x );
-	lgm = (x0 - x1)/(x1 + x0);
-	if( fabs(lgm) < dithresh )
-		break;
-	lgm = (y - y0)/y0;
-	if( fabs(lgm) < dithresh )
-		break;
-	if( x <= 0.0 )
-		break;
-	if( y >= y0 )
-		{
-		x1 = x;
-		yh = y;
-		if( dir < 0 )
-			{
-			dir = 0;
-			d = 0.5;
-			}
-		else if( dir > 1 )
-			d = 0.5 * d + 0.5; 
-		else
-			d = (y0 - yl)/(yh - yl);
-		dir += 1;
-		}
-	else
-		{
-		x0 = x;
-		yl = y;
-		if( dir > 0 )
-			{
-			dir = 0;
-			d = 0.5;
-			}
-		else if( dir < -1 )
-			d = 0.5 * d;
-		else
-			d = (y0 - yl)/(yh - yl);
-		dir -= 1;
-		}
-	}
-if( x == 0.0 )
-	mtherr( "igami", UNDERFLOW );
-
-done:
-return( x );
-}
-- 
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