diff mbox

[4/5] Use DO_SIN for sin(x) where 0.25 < |x| < 0.855469

Message ID 1471976565-3576-5-git-send-email-siddhesh@sourceware.org
State New
Headers show

Commit Message

Siddhesh Poyarekar Aug. 23, 2016, 6:22 p.m. UTC 
The only code looks slightly different from DO_SIN but on closer
examination, should give exactly the same result.  Drop it in favour
of the DO_SIN function call.

	* sysdeps/ieee754/dbl-64/s_sin.c (__sin): Use DO_SIN.
---
 sysdeps/ieee754/dbl-64/s_sin.c | 21 +++------------------
 1 file changed, 3 insertions(+), 18 deletions(-)

Comments

Siddhesh Poyarekar Aug. 30, 2016, 3:09 a.m. UTC | #1 
Ping!

On Tuesday 23 August 2016 11:52 PM, Siddhesh Poyarekar wrote:
> The only code looks slightly different from DO_SIN but on closer
> examination, should give exactly the same result.  Drop it in favour
> of the DO_SIN function call.
> 
> 	* sysdeps/ieee754/dbl-64/s_sin.c (__sin): Use DO_SIN.
> ---
>  sysdeps/ieee754/dbl-64/s_sin.c | 21 +++------------------
>  1 file changed, 3 insertions(+), 18 deletions(-)
> 
> diff --git a/sysdeps/ieee754/dbl-64/s_sin.c b/sysdeps/ieee754/dbl-64/s_sin.c
> index e03c75a..82f9345 100644
> --- a/sysdeps/ieee754/dbl-64/s_sin.c
> +++ b/sysdeps/ieee754/dbl-64/s_sin.c
> @@ -441,7 +441,7 @@ SECTION
>  #endif
>  __sin (double x)
>  {
> -  double xx, res, t, cor, y, s, c, sn, ssn, cs, ccs;
> +  double xx, res, t, cor;
>    mynumber u;
>    int4 k, m;
>    double retval = 0;
> @@ -471,23 +471,8 @@ __sin (double x)
>  /*---------------------------- 0.25<|x|< 0.855469---------------------- */
>    else if (k < 0x3feb6000)
>      {
> -      u.x = big + fabs (x);
> -      y = fabs (x) - (u.x - big);
> -      y = (x > 0 ? y : -y);
> -
> -      xx = y * y;
> -      s = y + y * xx * (sn3 + xx * sn5);
> -      c = xx * (cs2 + xx * (cs4 + xx * cs6));
> -      SINCOS_TABLE_LOOKUP (u, sn, ssn, cs, ccs);
> -      if (m <= 0)
> -        {
> -          sn = -sn;
> -	  ssn = -ssn;
> -	}
> -      cor = (ssn + s * ccs - sn * c) + cs * s;
> -      res = sn + cor;
> -      cor = (sn - res) + cor;
> -      retval = (res == res + 1.096 * cor) ? res : slow1 (x);
> +      res = do_sin (x, 0, &cor);
> +      retval = (res == res + 1.096 * cor) ? (m > 0 ? res : -res) : slow1 (x);
>      }				/*   else  if (k < 0x3feb6000)    */
>  
>  /*----------------------- 0.855469  <|x|<2.426265  ----------------------*/
>
Joseph Myers Sept. 1, 2016, 4:35 p.m. UTC | #2 
On Tue, 23 Aug 2016, Siddhesh Poyarekar wrote:

> The only code looks slightly different from DO_SIN but on closer
> examination, should give exactly the same result.  Drop it in favour
> of the DO_SIN function call.
> 
> 	* sysdeps/ieee754/dbl-64/s_sin.c (__sin): Use DO_SIN.

OK, but it's do_sin not DO_SIN; uppercasing only applies when referring to 
the value of a variable.
diff mbox

Patch

diff --git a/sysdeps/ieee754/dbl-64/s_sin.c b/sysdeps/ieee754/dbl-64/s_sin.c
index e03c75a..82f9345 100644
--- a/sysdeps/ieee754/dbl-64/s_sin.c
+++ b/sysdeps/ieee754/dbl-64/s_sin.c
@@ -441,7 +441,7 @@  SECTION
 #endif
 __sin (double x)
 {
-  double xx, res, t, cor, y, s, c, sn, ssn, cs, ccs;
+  double xx, res, t, cor;
   mynumber u;
   int4 k, m;
   double retval = 0;
@@ -471,23 +471,8 @@  __sin (double x)
 /*---------------------------- 0.25<|x|< 0.855469---------------------- */
   else if (k < 0x3feb6000)
     {
-      u.x = big + fabs (x);
-      y = fabs (x) - (u.x - big);
-      y = (x > 0 ? y : -y);
-
-      xx = y * y;
-      s = y + y * xx * (sn3 + xx * sn5);
-      c = xx * (cs2 + xx * (cs4 + xx * cs6));
-      SINCOS_TABLE_LOOKUP (u, sn, ssn, cs, ccs);
-      if (m <= 0)
-        {
-          sn = -sn;
-	  ssn = -ssn;
-	}
-      cor = (ssn + s * ccs - sn * c) + cs * s;
-      res = sn + cor;
-      cor = (sn - res) + cor;
-      retval = (res == res + 1.096 * cor) ? res : slow1 (x);
+      res = do_sin (x, 0, &cor);
+      retval = (res == res + 1.096 * cor) ? (m > 0 ? res : -res) : slow1 (x);
     }				/*   else  if (k < 0x3feb6000)    */
 
 /*----------------------- 0.855469  <|x|<2.426265  ----------------------*/