diff options
Diffstat (limited to 'sysdeps/libm-ieee754/s_expm1.c')
| -rw-r--r-- | sysdeps/libm-ieee754/s_expm1.c | 24 |
1 files changed, 17 insertions, 7 deletions
diff --git a/sysdeps/libm-ieee754/s_expm1.c b/sysdeps/libm-ieee754/s_expm1.c index c8354b7262..ed1aba527b 100644 --- a/sysdeps/libm-ieee754/s_expm1.c +++ b/sysdeps/libm-ieee754/s_expm1.c @@ -9,6 +9,9 @@ * is preserved. * ==================================================== */ +/* Modified by Naohiko Shimizu/Tokai University, Japan 1997/08/25, + for performance improvement on pipelined processors. +*/ #if defined(LIBM_SCCS) && !defined(lint) static char rcsid[] = "$NetBSD: s_expm1.c,v 1.8 1995/05/10 20:47:09 jtc Exp $"; @@ -111,7 +114,7 @@ static char rcsid[] = "$NetBSD: s_expm1.c,v 1.8 1995/05/10 20:47:09 jtc Exp $"; #include "math.h" #include "math_private.h" - +#define one Q[0] #ifdef __STDC__ static const double #else @@ -125,11 +128,11 @@ ln2_hi = 6.93147180369123816490e-01,/* 0x3fe62e42, 0xfee00000 */ ln2_lo = 1.90821492927058770002e-10,/* 0x3dea39ef, 0x35793c76 */ invln2 = 1.44269504088896338700e+00,/* 0x3ff71547, 0x652b82fe */ /* scaled coefficients related to expm1 */ -Q1 = -3.33333333333331316428e-02, /* BFA11111 111110F4 */ -Q2 = 1.58730158725481460165e-03, /* 3F5A01A0 19FE5585 */ -Q3 = -7.93650757867487942473e-05, /* BF14CE19 9EAADBB7 */ -Q4 = 4.00821782732936239552e-06, /* 3ED0CFCA 86E65239 */ -Q5 = -2.01099218183624371326e-07; /* BE8AFDB7 6E09C32D */ +Q[] = {1.0, -3.33333333333331316428e-02, /* BFA11111 111110F4 */ + 1.58730158725481460165e-03, /* 3F5A01A0 19FE5585 */ + -7.93650757867487942473e-05, /* BF14CE19 9EAADBB7 */ + 4.00821782732936239552e-06, /* 3ED0CFCA 86E65239 */ + -2.01099218183624371326e-07}; /* BE8AFDB7 6E09C32D */ #ifdef __STDC__ double __expm1(double x) @@ -138,7 +141,7 @@ Q5 = -2.01099218183624371326e-07; /* BE8AFDB7 6E09C32D */ double x; #endif { - double y,hi,lo,c,t,e,hxs,hfx,r1; + double y,hi,lo,c,t,e,hxs,hfx,r1,h2,h4,R1,R2,R3; int32_t k,xsb; u_int32_t hx; @@ -190,7 +193,14 @@ Q5 = -2.01099218183624371326e-07; /* BE8AFDB7 6E09C32D */ /* x is now in primary range */ hfx = 0.5*x; hxs = x*hfx; +#ifdef DO_NOT_USE_THIS r1 = one+hxs*(Q1+hxs*(Q2+hxs*(Q3+hxs*(Q4+hxs*Q5)))); +#else + R1 = one+hxs*Q[1]; h2 = hxs*hxs; + R2 = Q[2]+hxs*Q[3]; h4 = h2*h2; + R3 = Q[4]+hxs*Q[5]; + r1 = R1 + h2*R2 + h4*R3; +#endif t = 3.0-r1*hfx; e = hxs*((r1-t)/(6.0 - x*t)); if(k==0) return x - (x*e-hxs); /* c is 0 */ |