diff options
Diffstat (limited to 'sysdeps/libm-ieee754/s_atan.c')
| -rw-r--r-- | sysdeps/libm-ieee754/s_atan.c | 21 |
1 files changed, 20 insertions, 1 deletions
diff --git a/sysdeps/libm-ieee754/s_atan.c b/sysdeps/libm-ieee754/s_atan.c index 6657b15cda..cad3ba12a8 100644 --- a/sysdeps/libm-ieee754/s_atan.c +++ b/sysdeps/libm-ieee754/s_atan.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_atan.c,v 1.8 1995/05/10 20:46:45 jtc Exp $"; @@ -92,7 +95,7 @@ huge = 1.0e300; double x; #endif { - double w,s1,s2,z; + double w,s1,z,s,w2,w4,s11,s12,s13,s21,s22,s23; int32_t ix,hx,id; GET_HIGH_WORD(hx,x); @@ -129,6 +132,7 @@ huge = 1.0e300; z = x*x; w = z*z; /* break sum from i=0 to 10 aT[i]z**(i+1) into odd and even poly */ +#ifdef DO_NOT_USE_THIS s1 = z*(aT[0]+w*(aT[2]+w*(aT[4]+w*(aT[6]+w*(aT[8]+w*aT[10]))))); s2 = w*(aT[1]+w*(aT[3]+w*(aT[5]+w*(aT[7]+w*aT[9])))); if (id<0) return x - x*(s1+s2); @@ -136,6 +140,21 @@ huge = 1.0e300; z = atanhi[id] - ((x*(s1+s2) - atanlo[id]) - x); return (hx<0)? -z:z; } +#else + s11 = aT[8]+w*aT[10]; w2=w*w; + s12 = aT[4]+w*aT[6]; w4=w2*w2; + s13 = aT[0]+w*aT[2]; + s21 = aT[7]+w*aT[9]; + s22 = aT[3]+w*aT[5]; + s23 = w*aT[1]; + s1 = s13 + w2*s12 + w4*s11; + s = s23 + w2*s22 + w4*s21 + z*s1; + if (id<0) return x - x*(s); + else { + z = atanhi[id] - ((x*(s) - atanlo[id]) - x); + return (hx<0)? -z:z; + } +#endif } weak_alias (__atan, atan) #ifdef NO_LONG_DOUBLE |