forked from KolibriOS/kolibrios
upload sdk
git-svn-id: svn://kolibrios.org@4349 a494cfbc-eb01-0410-851d-a64ba20cac60
This commit is contained in:
Sergey Semyonov (Serge)
207
contrib/sdk/sources/newlib/math/ef_jn.c
Normal file
207
contrib/sdk/sources/newlib/math/ef_jn.c
Normal file
@@ -0,0 +1,207 @@
|
||||
/* ef_jn.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.
|
||||
* ====================================================
|
||||
*/
|
||||
|
||||
#include "fdlibm.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(FLT_UWORD_IS_NAN(ix)) 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(FLT_UWORD_IS_ZERO(ix)||FLT_UWORD_IS_INFINITE(ix))
|
||||
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(FLT_UWORD_IS_NAN(ix)) return x+x;
|
||||
if(FLT_UWORD_IS_ZERO(ix)) return -one/zero;
|
||||
if(hx<0) return zero/zero;
|
||||
sign = 1;
|
||||
if(n<0){
|
||||
n = -n;
|
||||
sign = 1 - ((n&1)<<1);
|
||||
}
|
||||
if(n==0) return(__ieee754_y0f(x));
|
||||
if(n==1) return(sign*__ieee754_y1f(x));
|
||||
if(FLT_UWORD_IS_INFINITE(ix)) 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;
|
||||
}
|
||||
Reference in New Issue
Block a user