X-Git-Url: http://erislabs.net/gitweb/?a=blobdiff_plain;f=lib%2Fsincosl.c;h=44f489c835c88d2858fed2c16396224a5ca279ed;hb=b94f2b3ac7049ef66bded4596431c453e3710209;hp=9fae568ae717196fab29755d1df0d8c1e143696f;hpb=73e329f11142c2804e42825e1590041d68dbb6e9;p=gnulib.git

diff --git a/lib/sincosl.c b/lib/sincosl.c
index 9fae568ae..44f489c83 100644
--- a/lib/sincosl.c
+++ b/lib/sincosl.c
@@ -1,5 +1,5 @@
 /* Quad-precision floating point trigonometric functions on <-pi/4,pi/4>.
-   Copyright (C) 1999, 2006, 2007, 2009-2010 Free Software Foundation, Inc.
+   Copyright (C) 1999, 2006-2007, 2009-2011 Free Software Foundation, Inc.
    This file is part of the GNU C Library.
    Contributed by Jakub Jelinek <jj@ultra.linux.cz>
 
@@ -136,11 +136,12 @@ kernel_sinl (long double x, long double y, int iy)
   else
     {
       /* So that we don't have to use too large polynomial,  we find
-         l and h such that x = l + h,  where fabsl(l) <= 1.0/256 with 83
-         possible values for h.  We look up cosl(h) and sinl(h) in
+         k and l such that x = k + l,  where fabsl(l) <= 1.0/256 with 83
+         possible values for k.  We look up cosl(k) and sinl(k) in
          pre-computed tables,  compute cosl(l) and sinl(l) using a
          Chebyshev polynomial of degree 10(11) and compute
-         sinl(h+l) = sinl(h)cosl(l) + cosl(h)sinl(l).  */
+         sinl(k+l) = sinl(k)cosl(l) + cosl(k)sinl(l).
+         Furthermore write k = 0.1484375 + h.  */
       x -= 0.1484375L;
       index = (int) (x * 128L + 0.5L);
       h = index / 128.0L;
@@ -158,11 +159,14 @@ kernel_sinl (long double x, long double y, int iy)
         z * (SCOS1 + z * (SCOS2 + z * (SCOS3 + z * (SCOS4 + z * SCOS5))));
 
       index *= 4;
+      /* We rely on this expression not being "contracted" by the compiler
+         (cf. ISO C 99 section 6.5 paragraph 8).  */
       z =
-        sincosl_table[index + SINCOSL_SIN_HI] +
-        (sincosl_table[index + SINCOSL_SIN_LO] +
-         (sincosl_table[index + SINCOSL_SIN_HI] * cos_l_m1) +
-         (sincosl_table[index + SINCOSL_COS_HI] * sin_l));
+        sincosl_table[index + SINCOSL_SIN_HI]
+        + (sincosl_table[index + SINCOSL_COS_HI] * sin_l
+           + (sincosl_table[index + SINCOSL_SIN_HI] * cos_l_m1
+              + (sincosl_table[index + SINCOSL_SIN_LO] * (1 + cos_l_m1)
+                 + sincosl_table[index + SINCOSL_COS_LO] * sin_l)));
       return z * sign;
     }
 }
@@ -195,11 +199,12 @@ kernel_cosl (long double x, long double y)
   else
     {
       /* So that we don't have to use too large polynomial,  we find
-         l and h such that x = l + h,  where fabsl(l) <= 1.0/256 with 83
-         possible values for h.  We look up cosl(h) and sinl(h) in
+         k and l such that x = k + l,  where fabsl(l) <= 1.0/256 with 83
+         possible values for k.  We look up cosl(k) and sinl(k) in
          pre-computed tables,  compute cosl(l) and sinl(l) using a
          Chebyshev polynomial of degree 10(11) and compute
-         sinl(h+l) = sinl(h)cosl(l) + cosl(h)sinl(l).  */
+         cosl(k+l) = cosl(k)cosl(l) - sinl(k)sinl(l).
+         Furthermore write k = 0.1484375 + h.  */
       x -= 0.1484375L;
       index = (int) (x * 128L + 0.5L);
       h = index / 128.0L;
@@ -213,10 +218,14 @@ kernel_cosl (long double x, long double y)
         z * (SCOS1 + z * (SCOS2 + z * (SCOS3 + z * (SCOS4 + z * SCOS5))));
 
       index *= 4;
-      z = sincosl_table [index + SINCOSL_COS_HI]
-          + (sincosl_table [index + SINCOSL_COS_LO]
-             - (sincosl_table [index + SINCOSL_SIN_HI] * sin_l)
-             - (sincosl_table [index + SINCOSL_COS_HI] * cos_l_m1));
+      /* We rely on this expression not being "contracted" by the compiler
+         (cf. ISO C 99 section 6.5 paragraph 8).  */
+      z =
+        sincosl_table [index + SINCOSL_COS_HI]
+        - (sincosl_table [index + SINCOSL_SIN_HI] * sin_l
+           - (sincosl_table [index + SINCOSL_COS_HI] * cos_l_m1
+              + (sincosl_table [index + SINCOSL_COS_LO] * (1 + cos_l_m1)
+                 - sincosl_table [index + SINCOSL_SIN_LO] * sin_l)));
       return z;
     }
 }