J.T. Conklin's latest version of the Sun math library.

-- Begin comments from J.T. Conklin:
The most significant improvement is the addition of "float" versions
of the math functions that take float arguments, return floats, and do
all operations in floating point.  This doesn't help (performance)
much on the i386, but they are still nice to have.

The float versions were orginally done by Cygnus' Ian Taylor when
fdlibm was integrated into the libm we support for embedded systems.
I gave Ian a copy of my libm as a starting point since I had already
fixed a lot of bugs & problems in Sun's original code.  After he was
done, I cleaned it up a bit and integrated the changes back into my
libm.
-- End comments

Reviewed by:	jkh
Submitted by:	jtc

1 files changed, 212 insertions, 0 deletions

diff --git a/lib/msun/src/e_jnf.c b/lib/msun/src/e_jnf.c
new file mode 100644
index 0000000..edca14a
--- /dev/null
+++ b/lib/msun/src/e_jnf.c
@@ -0,0 +1,212 @@
+/* e_jnf.c -- float version of e_jn.c.
+ * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
+ */
+
+/*
+ * ====================================================
+ * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
+ *
+ * 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.
+ * ====================================================
+ */
+
+#ifndef lint
+static char rcsid[] = "$Id: e_jnf.c,v 1.2 1994/08/18 23:05:39 jtc Exp $";
+#endif
+
+#include "math.h"
+#include "math_private.h"
+
+#ifdef __STDC__
+static const float
+#else
+static float
+#endif
+invsqrtpi=  5.6418961287e-01, /* 0x3f106ebb */
+two   =  2.0000000000e+00, /* 0x40000000 */
+one   =  1.0000000000e+00; /* 0x3F800000 */
+
+#ifdef __STDC__
+static const float zero  =  0.0000000000e+00;
+#else
+static float zero  =  0.0000000000e+00;
+#endif
+
+#ifdef __STDC__
+	float __ieee754_jnf(int n, float x)
+#else
+	float __ieee754_jnf(n,x)
+	int n; float x;
+#endif
+{
+	int32_t i,hx,ix, sgn;
+	float a, b, temp, di;
+	float z, w;
+
+    /* J(-n,x) = (-1)^n * J(n, x), J(n, -x) = (-1)^n * J(n, x)
+     * Thus, J(-n,x) = J(n,-x)
+     */
+	GET_FLOAT_WORD(hx,x);
+	ix = 0x7fffffff&hx;
+    /* if J(n,NaN) is NaN */
+	if(ix>0x7f800000) return x+x;
+	if(n<0){		
+		n = -n;
+		x = -x;
+		hx ^= 0x80000000;
+	}
+	if(n==0) return(__ieee754_j0f(x));
+	if(n==1) return(__ieee754_j1f(x));
+	sgn = (n&1)&(hx>>31);	/* even n -- 0, odd n -- sign(x) */
+	x = fabsf(x);
+	if(ix==0||ix>=0x7f800000) 	/* if x is 0 or inf */
+	    b = zero;
+	else if((float)n<=x) {   
+		/* Safe to use J(n+1,x)=2n/x *J(n,x)-J(n-1,x) */
+	    a = __ieee754_j0f(x);
+	    b = __ieee754_j1f(x);
+	    for(i=1;i<n;i++){
+		temp = b;
+		b = b*((float)(i+i)/x) - a; /* avoid underflow */
+		a = temp;
+	    }
+	} else {
+	    if(ix<0x30800000) {	/* x < 2**-29 */
+    /* x is tiny, return the first Taylor expansion of J(n,x) 
+     * J(n,x) = 1/n!*(x/2)^n  - ...
+     */
+		if(n>33)	/* underflow */
+		    b = zero;
+		else {
+		    temp = x*(float)0.5; b = temp;
+		    for (a=one,i=2;i<=n;i++) {
+			a *= (float)i;		/* a = n! */
+			b *= temp;		/* b = (x/2)^n */
+		    }
+		    b = b/a;
+		}
+	    } else {
+		/* use backward recurrence */
+		/* 			x      x^2      x^2       
+		 *  J(n,x)/J(n-1,x) =  ----   ------   ------   .....
+		 *			2n  - 2(n+1) - 2(n+2)
+		 *
+		 * 			1      1        1       
+		 *  (for large x)   =  ----  ------   ------   .....
+		 *			2n   2(n+1)   2(n+2)
+		 *			-- - ------ - ------ - 
+		 *			 x     x         x
+		 *
+		 * Let w = 2n/x and h=2/x, then the above quotient
+		 * is equal to the continued fraction:
+		 *		    1
+		 *	= -----------------------
+		 *		       1
+		 *	   w - -----------------
+		 *			  1
+		 * 	        w+h - ---------
+		 *		       w+2h - ...
+		 *
+		 * To determine how many terms needed, let
+		 * Q(0) = w, Q(1) = w(w+h) - 1,
+		 * Q(k) = (w+k*h)*Q(k-1) - Q(k-2),
+		 * When Q(k) > 1e4	good for single 
+		 * When Q(k) > 1e9	good for double 
+		 * When Q(k) > 1e17	good for quadruple 
+		 */
+	    /* determine k */
+		float t,v;
+		float q0,q1,h,tmp; int32_t k,m;
+		w  = (n+n)/(float)x; h = (float)2.0/(float)x;
+		q0 = w;  z = w+h; q1 = w*z - (float)1.0; k=1;
+		while(q1<(float)1.0e9) {
+			k += 1; z += h;
+			tmp = z*q1 - q0;
+			q0 = q1;
+			q1 = tmp;
+		}
+		m = n+n;
+		for(t=zero, i = 2*(n+k); i>=m; i -= 2) t = one/(i/x-t);
+		a = t;
+		b = one;
+		/*  estimate log((2/x)^n*n!) = n*log(2/x)+n*ln(n)
+		 *  Hence, if n*(log(2n/x)) > ...
+		 *  single 8.8722839355e+01
+		 *  double 7.09782712893383973096e+02
+		 *  long double 1.1356523406294143949491931077970765006170e+04
+		 *  then recurrent value may overflow and the result is 
+		 *  likely underflow to zero
+		 */
+		tmp = n;
+		v = two/x;
+		tmp = tmp*__ieee754_logf(fabsf(v*tmp));
+		if(tmp<(float)8.8721679688e+01) {
+	    	    for(i=n-1,di=(float)(i+i);i>0;i--){
+		        temp = b;
+			b *= di;
+			b  = b/x - a;
+		        a = temp;
+			di -= two;
+	     	    }
+		} else {
+	    	    for(i=n-1,di=(float)(i+i);i>0;i--){
+		        temp = b;
+			b *= di;
+			b  = b/x - a;
+		        a = temp;
+			di -= two;
+		    /* scale b to avoid spurious overflow */
+			if(b>(float)1e10) {
+			    a /= b;
+			    t /= b;
+			    b  = one;
+			}
+	     	    }
+		}
+	    	b = (t*__ieee754_j0f(x)/b);
+	    }
+	}
+	if(sgn==1) return -b; else return b;
+}
+
+#ifdef __STDC__
+	float __ieee754_ynf(int n, float x) 
+#else
+	float __ieee754_ynf(n,x) 
+	int n; float x;
+#endif
+{
+	int32_t i,hx,ix,ib;
+	int32_t sign;
+	float a, b, temp;
+
+	GET_FLOAT_WORD(hx,x);
+	ix = 0x7fffffff&hx;
+    /* if Y(n,NaN) is NaN */
+	if(ix>0x7f800000) return x+x;
+	if(ix==0) return -one/zero;
+	if(hx<0) return zero/zero;
+	sign = 1;
+	if(n<0){
+		n = -n;
+		sign = 1 - ((n&1)<<2);
+	}
+	if(n==0) return(__ieee754_y0f(x));
+	if(n==1) return(sign*__ieee754_y1f(x));
+	if(ix==0x7f800000) return zero;
+
+	a = __ieee754_y0f(x);
+	b = __ieee754_y1f(x);
+	/* quit if b is -inf */
+	GET_FLOAT_WORD(ib,b);
+	for(i=1;i<n&&ib!=0xff800000;i++){ 
+	    temp = b;
+	    b = ((float)(i+i)/x)*b - a;
+	    GET_FLOAT_WORD(ib,b);
+	    a = temp;
+	}
+	if(sign>0) return b; else return -b;
+}