WebSVN – Kolibri OS – Diff – /programs/develop/libraries/newlib/math/s_erf.c

-/* @(#)s_erf.c 1.3 95/01/18 */
+/* @(#)s_erf.c 5.1 93/09/24 */
 /*
  * ====================================================
  * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
+ *
- * Developed at SunSoft, a Sun Microsystems, Inc. business.
+ * Developed at SunPro, a Sun Microsystems, Inc. business.
  * Permission to use, copy, modify, and distribute this
  * software is freely granted, provided that this notice
  * is preserved.
  * ====================================================
  */
+/*
+FUNCTION
+        <>, <>, <>, <>---error function
+INDEX
+	erf
+INDEX
+	erff
+INDEX
+	erfc
+INDEX
+	erfcf
+ANSI_SYNOPSIS
+	#include
+	double erf(double <[x]>);
+	float erff(float <[x]>);
+	double erfc(double <[x]>);
+	float erfcf(float <[x]>);
+TRAD_SYNOPSIS
+	#include
+	double erf(<[x]>)
+	double <[x]>;
+	float erff(<[x]>)
+	float <[x]>;
+	double erfc(<[x]>)
+	double <[x]>;
+	float erfcf(<[x]>)
+	float <[x]>;
+DESCRIPTION
+	<> calculates an approximation to the ``error function'',
+	which estimates the probability that an observation will fall within
+	<[x]> standard deviations of the mean (assuming a normal
+	distribution).
+	@tex
+	The error function is defined as
+	$${2\over\sqrt\pi}\times\int_0^x e^{-t^2}dt$$
+	 @end tex
+	<> calculates the complementary probability; that is,
+	<)>> is <<1 - erf(<[x]>)>>.  <> is computed directly,
+	so that you can use it to avoid the loss of precision that would
+	result from subtracting large probabilities (on large <[x]>) from 1.
+	<> and <> differ from <> and <> only in the
+	argument and result types.
+RETURNS
+	For positive arguments, <> and all its variants return a
+	probability---a number between 0 and 1.
+PORTABILITY
+	None of the variants of <> are ANSI C.
+*/
 /* double erf(double x)
  * double erfc(double x)
  *			     x
  *		      2      |\
  *	   	erfc/erf(NaN) is NaN
  */
-/* #include "fdlibm.h" */
-#include
-#include
-#include
-#define __ieee754_exp exp
-typedef union
-{
-  double value;
-  struct
-  {
-    uint32_t lsw;
-    uint32_t msw;
-  } parts;
-} ieee_double_shape_type;
-static inline int __get_hi_word(const double x)
-{
-  ieee_double_shape_type u;
-  u.value = x;
-  return u.parts.msw;
-}
-static inline void __trunc_lo_word(double *x)
-{
-  ieee_double_shape_type u;
-  u.value = *x;
-  u.parts.lsw = 0;
-  *x = u.value;
+#include "fdlibm.h"
 #ifndef _DOUBLE_IS_32BITS
 #ifdef __STDC__
 	double erf(x)
 	double x;
 #endif
+{
-	int hx,ix,i;
+	__int32_t hx,ix,i;
 	double R,S,P,Q,s,y,z,r;
-	hx = __get_hi_word(x);
+	GET_HIGH_WORD(hx,x);
 	ix = hx&0x7fffffff;
 	if(ix>=0x7ff00000) {		/* erf(nan)=nan */
-	    i = ((unsigned)hx>>31)<<1;
+	    i = ((__uint32_t)hx>>31)<<1;
 	    return (double)(1-i)+one/x;	/* erf(+-inf)=+-1 */
+	}
 	if(ix < 0x3feb0000) {		/* |x|<0.84375 */
 	    if(ix < 0x3e300000) { 	/* |x|<2**-28 */
 	    S=one+s*(sb1+s*(sb2+s*(sb3+s*(sb4+s*(
 				sb5+s*(sb6+s*sb7))))));
+	}
 	z  = x;
-	__trunc_lo_word(&z);
+	SET_LOW_WORD(z,0);
 	r  =  __ieee754_exp(-z*z-0.5625)*__ieee754_exp((z-x)*(z+x)+R/S);
 	if(hx>=0) return one-r/x; else return  r/x-one;
+}
 #ifdef __STDC__
 	double erfc(x)
 	double x;
 #endif
+{
-	int hx,ix;
+	__int32_t hx,ix;
 	double R,S,P,Q,s,y,z,r;
-	hx = __get_hi_word(x);
+	GET_HIGH_WORD(hx,x);
 	ix = hx&0x7fffffff;
 	if(ix>=0x7ff00000) {			/* erfc(nan)=nan */
 						/* erfc(+-inf)=0,2 */
-	    return (double)(((unsigned)hx>>31)<<1)+one/x;
+	    return (double)(((__uint32_t)hx>>31)<<1)+one/x;
 	}
 	if(ix < 0x3feb0000) {		/* |x|<0.84375 */
 	    if(ix < 0x3c700000)  	/* |x|<2**-56 */
 		return one-x;
 	        S=one+s*(sb1+s*(sb2+s*(sb3+s*(sb4+s*(
 				sb5+s*(sb6+s*sb7))))));
+	    }
 	    z  = x;
-	    __trunc_lo_word(&z);
+	    SET_LOW_WORD(z,0);
 	    r  =  __ieee754_exp(-z*z-0.5625)*
 			__ieee754_exp((z-x)*(z+x)+R/S);
 	    if(hx>0) return r/x; else return two-r/x;
 	} else {
-	    /* set range error */
+	    if(hx>0) return tiny*tiny; else return two-tiny;
-            errno = ERANGE;
-	    if(hx>0) return tiny*tiny; else return two-tiny;
+	}
+}
+#endif /* _DOUBLE_IS_32BITS */
+>

Subversion Repositories Kolibri OS

(root)/programs/develop/libraries/newlib/math/s_erf.c – Rev 1906 → 3362