diff options
Diffstat (limited to 'sysdeps/libm-ieee754/s_log1p.c')
| -rw-r--r-- | sysdeps/libm-ieee754/s_log1p.c | 27 |
1 files changed, 19 insertions, 8 deletions
diff --git a/sysdeps/libm-ieee754/s_log1p.c b/sysdeps/libm-ieee754/s_log1p.c index 086c0dce6c..4ca01b1ff5 100644 --- a/sysdeps/libm-ieee754/s_log1p.c +++ b/sysdeps/libm-ieee754/s_log1p.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_log1p.c,v 1.8 1995/05/10 20:47:46 jtc Exp $"; @@ -90,13 +93,13 @@ static double ln2_hi = 6.93147180369123816490e-01, /* 3fe62e42 fee00000 */ ln2_lo = 1.90821492927058770002e-10, /* 3dea39ef 35793c76 */ two54 = 1.80143985094819840000e+16, /* 43500000 00000000 */ -Lp1 = 6.666666666666735130e-01, /* 3FE55555 55555593 */ -Lp2 = 3.999999999940941908e-01, /* 3FD99999 9997FA04 */ -Lp3 = 2.857142874366239149e-01, /* 3FD24924 94229359 */ -Lp4 = 2.222219843214978396e-01, /* 3FCC71C5 1D8E78AF */ -Lp5 = 1.818357216161805012e-01, /* 3FC74664 96CB03DE */ -Lp6 = 1.531383769920937332e-01, /* 3FC39A09 D078C69F */ -Lp7 = 1.479819860511658591e-01; /* 3FC2F112 DF3E5244 */ +Lp[] = {0.0, 6.666666666666735130e-01, /* 3FE55555 55555593 */ + 3.999999999940941908e-01, /* 3FD99999 9997FA04 */ + 2.857142874366239149e-01, /* 3FD24924 94229359 */ + 2.222219843214978396e-01, /* 3FCC71C5 1D8E78AF */ + 1.818357216161805012e-01, /* 3FC74664 96CB03DE */ + 1.531383769920937332e-01, /* 3FC39A09 D078C69F */ + 1.479819860511658591e-01}; /* 3FC2F112 DF3E5244 */ #ifdef __STDC__ static const double zero = 0.0; @@ -111,7 +114,7 @@ static double zero = 0.0; double x; #endif { - double hfsq,f,c,s,z,R,u; + double hfsq,f,c,s,z,R,u,z2,z4,z6,R1,R2,R3,R4; int32_t k,hx,hu,ax; GET_HIGH_WORD(hx,x); @@ -167,7 +170,15 @@ static double zero = 0.0; } s = f/(2.0+f); z = s*s; +#ifdef DO_NOT_USE_THIS R = z*(Lp1+z*(Lp2+z*(Lp3+z*(Lp4+z*(Lp5+z*(Lp6+z*Lp7)))))); +#else + R1 = z*Lp[1]; z2=z*z; + R2 = Lp[2]+z*Lp[3]; z4=z2*z2; + R3 = Lp[4]+z*Lp[5]; z6=z4*z2; + R4 = Lp[6]+z*Lp[7]; + R = R1 + z2*R2 + z4*R3 + z6*R4; +#endif if(k==0) return f-(hfsq-s*(hfsq+R)); else return k*ln2_hi-((hfsq-(s*(hfsq+R)+(k*ln2_lo+c)))-f); } |