mirror of git://sourceware.org/git/glibc.git
Remove more redundant computations in s_sin.c
Removed more redundant computations in the slow paths of the sin and cos functions. The notable change is the passing of the most significant bits of X to the slow functions to check if X is positive so that just the absolute value of x can be passed and the repeated ABS() operation is avoided.
This commit is contained in:
Siddhesh Poyarekar
parent
975195e466
commit
84ba214c21
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@ -1,5 +1,12 @@
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2013-12-20 Siddhesh Poyarekar <siddhesh@redhat.com>
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* sysdeps/ieee754/dbl-64/s_sin.c (sloww1): Add new argument M.
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Use M to change sign of result instead of X. Assume X is
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positive.
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(csloww1): Likewise.
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(__sin): Adjust.
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(__cos): Adjust.
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* sysdeps/ieee754/dbl-64/s_sin.c (reduce_and_compute): Remove
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arguments A and DA.
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(__sin): Adjust.
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@ -134,7 +134,7 @@ static double slow (double x);
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static double slow1 (double x);
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static double slow2 (double x);
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static double sloww (double x, double dx, double orig);
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static double sloww1 (double x, double dx, double orig);
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static double sloww1 (double x, double dx, double orig, int m);
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static double sloww2 (double x, double dx, double orig, int n);
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static double bsloww (double x, double dx, double orig, int n);
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static double bsloww1 (double x, double dx, double orig, int n);
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@ -142,7 +142,7 @@ static double bsloww2 (double x, double dx, double orig, int n);
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int __branred (double x, double *a, double *aa);
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static double cslow2 (double x);
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static double csloww (double x, double dx, double orig);
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static double csloww1 (double x, double dx, double orig);
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static double csloww1 (double x, double dx, double orig, int m);
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static double csloww2 (double x, double dx, double orig, int n);
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/* Reduce range of X and compute sin of a + da. K is the amount by which to
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@ -287,18 +287,15 @@ __sin (double x)
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else
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{
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if (a > 0)
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{
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m = 1;
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t = a;
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}
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m = 1;
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else
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{
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m = 0;
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t = -a;
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a = -a;
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da = -da;
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}
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u.x = big + t;
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y = t - (u.x - big);
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u.x = big + a;
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y = a - (u.x - big);
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xx = y * y;
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s = y + (da + y * xx * (sn3 + xx * sn5));
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c = y * da + xx * (cs2 + xx * (cs4 + xx * cs6));
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@ -308,7 +305,7 @@ __sin (double x)
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cor = (sn - res) + cor;
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cor = (cor > 0) ? 1.035 * cor + eps : 1.035 * cor - eps;
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retval = ((res == res + cor) ? ((m) ? res : -res)
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: sloww1 (a, da, x));
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: sloww1 (a, da, x, m));
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}
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break;
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@ -375,17 +372,16 @@ __sin (double x)
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if (a > 0)
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{
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m = 1;
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t = a;
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db = da;
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}
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else
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{
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m = 0;
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t = -a;
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a = -a;
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db = -da;
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}
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u.x = big + t;
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y = t - (u.x - big);
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u.x = big + a;
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y = a - (u.x - big);
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xx = y * y;
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s = y + (db + y * xx * (sn3 + xx * sn5));
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c = y * db + xx * (cs2 + xx * (cs4 + xx * cs6));
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@ -496,16 +492,15 @@ __cos (double x)
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if (a > 0)
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{
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m = 1;
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t = a;
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}
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else
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{
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m = 0;
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t = -a;
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a = -a;
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da = -da;
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}
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u.x = big + t;
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y = t - (u.x - big);
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u.x = big + a;
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y = a - (u.x - big);
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xx = y * y;
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s = y + (da + y * xx * (sn3 + xx * sn5));
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c = y * da + xx * (cs2 + xx * (cs4 + xx * cs6));
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@ -515,7 +510,7 @@ __cos (double x)
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cor = (sn - res) + cor;
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cor = (cor > 0) ? 1.035 * cor + 1.0e-31 : 1.035 * cor - 1.0e-31;
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retval = ((res == res + cor) ? ((m) ? res : -res)
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: csloww1 (a, da, x));
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: csloww1 (a, da, x, m));
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}
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} /* else if (k < 0x400368fd) */
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@ -554,16 +549,15 @@ __cos (double x)
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if (a > 0)
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{
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m = 1;
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t = a;
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}
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else
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{
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m = 0;
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t = -a;
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a = -a;
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da = -da;
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}
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u.x = big + t;
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y = t - (u.x - big);
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u.x = big + a;
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y = a - (u.x - big);
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xx = y * y;
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s = y + (da + y * xx * (sn3 + xx * sn5));
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c = y * da + xx * (cs2 + xx * (cs4 + xx * cs6));
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@ -573,7 +567,7 @@ __cos (double x)
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cor = (sn - res) + cor;
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cor = (cor > 0) ? 1.035 * cor + eps : 1.035 * cor - eps;
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retval = ((res == res + cor) ? ((m) ? res : -res)
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: csloww1 (a, da, x));
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: csloww1 (a, da, x, m));
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}
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break;
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@ -638,17 +632,16 @@ __cos (double x)
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if (a > 0)
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{
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m = 1;
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t = a;
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db = da;
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}
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else
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{
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m = 0;
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t = -a;
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a = -a;
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db = -da;
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}
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u.x = big + t;
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y = t - (u.x - big);
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u.x = big + a;
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y = a - (u.x - big);
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xx = y * y;
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s = y + (db + y * xx * (sn3 + xx * sn5));
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c = y * db + xx * (cs2 + xx * (cs4 + xx * cs6));
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@ -888,14 +881,13 @@ sloww (double x, double dx, double orig)
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static double
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SECTION
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sloww1 (double x, double dx, double orig)
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sloww1 (double x, double dx, double orig, int m)
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{
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mynumber u;
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double sn, ssn, cs, ccs, s, c, w[2], y, y1, y2, c1, c2, xx, cor, res;
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y = ABS (x);
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u.x = big + y;
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y = y - (u.x - big);
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u.x = big + x;
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y = x - (u.x - big);
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xx = y * y;
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s = y * xx * (sn3 + xx * sn5);
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c = xx * (cs2 + xx * (cs4 + xx * cs6));
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@ -916,10 +908,10 @@ sloww1 (double x, double dx, double orig)
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cor = 1.0005 * cor - 3.1e-30 * ABS (orig);
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if (res == res + cor)
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return (x > 0) ? res : -res;
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return (m > 0) ? res : -res;
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else
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{
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__dubsin (ABS (x), dx, w);
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__dubsin (x, dx, w);
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if (w[1] > 0)
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cor = 1.000000005 * w[1] + 1.1e-30 * ABS (orig);
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@ -927,7 +919,7 @@ sloww1 (double x, double dx, double orig)
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cor = 1.000000005 * w[1] - 1.1e-30 * ABS (orig);
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if (w[0] == w[0] + cor)
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return (x > 0) ? w[0] : -w[0];
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return (m > 0) ? w[0] : -w[0];
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else
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return __mpsin (orig, 0, true);
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}
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@ -1240,14 +1232,13 @@ csloww (double x, double dx, double orig)
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static double
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SECTION
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csloww1 (double x, double dx, double orig)
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csloww1 (double x, double dx, double orig, int m)
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{
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mynumber u;
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double sn, ssn, cs, ccs, s, c, w[2], y, y1, y2, c1, c2, xx, cor, res;
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y = ABS (x);
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u.x = big + y;
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y = y - (u.x - big);
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u.x = big + x;
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y = x - (u.x - big);
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xx = y * y;
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s = y * xx * (sn3 + xx * sn5);
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c = xx * (cs2 + xx * (cs4 + xx * cs6));
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@ -1268,16 +1259,16 @@ csloww1 (double x, double dx, double orig)
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cor = 1.0005 * cor - 3.1e-30 * ABS (orig);
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if (res == res + cor)
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return (x > 0) ? res : -res;
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return (m > 0) ? res : -res;
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else
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{
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__dubsin (ABS (x), dx, w);
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__dubsin (x, dx, w);
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if (w[1] > 0)
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cor = 1.000000005 * w[1] + 1.1e-30 * ABS (orig);
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else
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cor = 1.000000005 * w[1] - 1.1e-30 * ABS (orig);
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if (w[0] == w[0] + cor)
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return (x > 0) ? w[0] : -w[0];
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return (m > 0) ? w[0] : -w[0];
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else
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return __mpcos (orig, 0, true);
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}
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