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/float/stdtrf.c | 154 ----------------------------------------------------
 1 file changed, 154 deletions(-)
 delete mode 100644 libm/float/stdtrf.c

(limited to 'libm/float/stdtrf.c')

diff --git a/libm/float/stdtrf.c b/libm/float/stdtrf.c
deleted file mode 100644
index 76b14c1f6..000000000
--- a/libm/float/stdtrf.c
+++ /dev/null
@@ -1,154 +0,0 @@
-/*							stdtrf.c
- *
- *	Student's t distribution
- *
- *
- *
- * SYNOPSIS:
- *
- * float t, stdtrf();
- * short k;
- *
- * y = stdtrf( k, t );
- *
- *
- * DESCRIPTION:
- *
- * Computes the integral from minus infinity to t of the Student
- * t distribution with integer k > 0 degrees of freedom:
- *
- *                                      t
- *                                      -
- *                                     | |
- *              -                      |         2   -(k+1)/2
- *             | ( (k+1)/2 )           |  (     x   )
- *       ----------------------        |  ( 1 + --- )        dx
- *                     -               |  (      k  )
- *       sqrt( k pi ) | ( k/2 )        |
- *                                   | |
- *                                    -
- *                                   -inf.
- * 
- * Relation to incomplete beta integral:
- *
- *        1 - stdtr(k,t) = 0.5 * incbet( k/2, 1/2, z )
- * where
- *        z = k/(k + t**2).
- *
- * For t < -1, this is the method of computation.  For higher t,
- * a direct method is derived from integration by parts.
- * Since the function is symmetric about t=0, the area under the
- * right tail of the density is found by calling the function
- * with -t instead of t.
- * 
- * ACCURACY:
- *
- *                      Relative error:
- * arithmetic   domain     # trials      peak         rms
- *    IEEE      +/- 100      5000       2.3e-5      2.9e-6
- */
-
-
-/*
-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>
-
-extern float PIF, MACHEPF;
-
-#ifdef ANSIC
-float sqrtf(float), atanf(float), incbetf(float, float, float);
-#else
-float sqrtf(), atanf(), incbetf();
-#endif
-
-
-
-float stdtrf( int k, float tt )
-{
-float t, x, rk, z, f, tz, p, xsqk;
-int j;
-
-t = tt;
-if( k <= 0 )
-	{
-	mtherr( "stdtrf", DOMAIN );
-	return(0.0);
-	}
-
-if( t == 0 )
-	return( 0.5 );
-
-if( t < -1.0 )
-	{
-	rk = k;
-	z = rk / (rk + t * t);
-	p = 0.5 * incbetf( 0.5*rk, 0.5, z );
-	return( p );
-	}
-
-/*	compute integral from -t to + t */
-
-if( t < 0 )
-	x = -t;
-else
-	x = t;
-
-rk = k;	/* degrees of freedom */
-z = 1.0 + ( x * x )/rk;
-
-/* test if k is odd or even */
-if( (k & 1) != 0)
-	{
-
-	/*	computation for odd k	*/
-
-	xsqk = x/sqrtf(rk);
-	p = atanf( xsqk );
-	if( k > 1 )
-		{
-		f = 1.0;
-		tz = 1.0;
-		j = 3;
-		while(  (j<=(k-2)) && ( (tz/f) > MACHEPF )  )
-			{
-			tz *= (j-1)/( z * j );
-			f += tz;
-			j += 2;
-			}
-		p += f * xsqk/z;
-		}
-	p *= 2.0/PIF;
-	}
-
-
-else
-	{
-
-	/*	computation for even k	*/
-
-	f = 1.0;
-	tz = 1.0;
-	j = 2;
-
-	while(  ( j <= (k-2) ) && ( (tz/f) > MACHEPF )  )
-		{
-		tz *= (j - 1)/( z * j );
-		f += tz;
-		j += 2;
-		}
-	p = f * x/sqrtf(z*rk);
-	}
-
-/*	common exit	*/
-
-
-if( t < 0 )
-	p = -p;	/* note destruction of relative accuracy */
-
-	p = 0.5 + 0.5 * p;
-return(p);
-}
-- 
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