diff mbox series

[v2,1/5] Remove remaining slow paths from asin and acos

Message ID VE1PR08MB5599A86F36F49CF1957B24F583AF0@VE1PR08MB5599.eurprd08.prod.outlook.com
State New
Headers show
Series [v2,1/5] Remove remaining slow paths from asin and acos | expand

Commit Message

Wilco Dijkstra Jan. 7, 2021, 7:23 p.m. UTC
This patch series removes all remaining slow paths and related code. First asin/acos, tan,
atan, atan2 implementations are updated, and the final patch removes the unused mpa files,
headers and probes. Passes buildmanyglibc.

Remove slow paths from asin/acos. Add ULP annotations based on previous slow path checks
(which may not be accurate). Update AArch64 libm-test-ulps for asin.

Passes GLIBC testsuite.

---
diff mbox series

Patch

diff --git a/sysdeps/aarch64/libm-test-ulps b/sysdeps/aarch64/libm-test-ulps
index 22fcf8db73dc444c25e0c356b1e0036571edd112..bbadf667ee4b7a0cf80506d321553f064049c516 100644
--- a/sysdeps/aarch64/libm-test-ulps
+++ b/sysdeps/aarch64/libm-test-ulps
@@ -41,6 +41,7 @@  float: 2
 ldouble: 2
 
 Function: "asin":
+double: 1
 float: 1
 ldouble: 1
 
@@ -55,7 +56,7 @@  float: 1
 ldouble: 1
 
 Function: "asin_upward":
-double: 1
+double: 2
 float: 1
 ldouble: 2
 
diff --git a/sysdeps/ieee754/dbl-64/e_asin.c b/sysdeps/ieee754/dbl-64/e_asin.c
index ae5344f720055ef31b01c4af2e1228b79b821430..4473ae5df41c31e80e8fd0d74a840e8b9e718a7d 100644
--- a/sysdeps/ieee754/dbl-64/e_asin.c
+++ b/sysdeps/ieee754/dbl-64/e_asin.c
@@ -21,8 +21,7 @@ 
 /*                                                                */
 /*     FUNCTIONS: uasin                                           */
 /*                uacos                                           */
-/* FILES NEEDED: dla.h endian.h mpa.h mydefs.h  usncs.h           */
-/*               doasin.c sincos32.c dosincos.c mpa.c             */
+/* FILES NEEDED: dla.h endian.h mydefs.h  usncs.h                 */
 /*               sincos.tbl  asincos.tbl  powtwo.tbl root.tbl     */
 /*                                                                */
 /******************************************************************/
@@ -31,7 +30,6 @@ 
 #include "asincos.tbl"
 #include "root.tbl"
 #include "powtwo.tbl"
-#include "MathLib.h"
 #include "uasncs.h"
 #include <float.h>
 #include <math.h>
@@ -43,15 +41,11 @@ 
 # define SECTION
 #endif
 
-void __doasin(double x, double dx, double w[]);
-void __dubsin(double x, double dx, double v[]);
-void __dubcos(double x, double dx, double v[]);
-void __docos(double x, double dx, double v[]);
-
+/* asin with max ULP of ~0.516 based on random sampling.  */
 double
 SECTION
 __ieee754_asin(double x){
-  double x1,x2,xx,s1,s2,res1,p,t,res,r,cor,cc,y,c,z,w[2];
+  double x2,xx,res1,p,t,res,r,cor,cc,y,c,z;
   mynumber u,v;
   int4 k,m,n;
 
@@ -70,27 +64,8 @@  __ieee754_asin(double x){
     x2 = x*x;
     t = (((((f6*x2 + f5)*x2 + f4)*x2 + f3)*x2 + f2)*x2 + f1)*(x2*x);
     res = x+t;         /*  res=arcsin(x) according to Taylor series  */
-    cor = (x-res)+t;
-    if (res == res+1.025*cor) return res;
-    else {
-      x1 = x+big;
-      xx = x*x;
-      x1 -= big;
-      x2 = x - x1;
-      p = x1*x1*x1;
-      s1 = a1.x*p;
-      s2 = ((((((c7*xx + c6)*xx + c5)*xx + c4)*xx + c3)*xx + c2)*xx*xx*x +
-	     ((a1.x+a2.x)*x2*x2+ 0.5*x1*x)*x2) + a2.x*p;
-      res1 = x+s1;
-      s2 = ((x-res1)+s1)+s2;
-      res = res1+s2;
-      cor = (res1-res)+s2;
-      if (res == res+1.00014*cor) return res;
-      else {
-	__doasin(x,0,w);
-	return w[0];
-      }
-    }
+    /* Max ULP is 0.513.  */
+    return res;
   }
   /*---------------------0.125 <= |x| < 0.5 -----------------------------*/
   else if (k < 0x3fe00000) {
@@ -103,26 +78,8 @@  __ieee754_asin(double x){
      +xx*asncs.x[n+6]))))+asncs.x[n+7];
     t+=p;
     res =asncs.x[n+8] +t;
-    cor = (asncs.x[n+8]-res)+t;
-    if (res == res+1.05*cor) return (m>0)?res:-res;
-    else {
-      r=asncs.x[n+8]+xx*asncs.x[n+9];
-      t=((asncs.x[n+8]-r)+xx*asncs.x[n+9])+(p+xx*asncs.x[n+10]);
-      res = r+t;
-      cor = (r-res)+t;
-      if (res == res+1.0005*cor) return (m>0)?res:-res;
-      else {
-	res1=res+1.1*cor;
-	z=0.5*(res1-res);
-	__dubsin(res,z,w);
-	z=(w[0]-fabs(x))+w[1];
-	if (z>1.0e-27) return (m>0)?min(res,res1):-min(res,res1);
-	else if (z<-1.0e-27) return (m>0)?max(res,res1):-max(res,res1);
-	else {
-	  return (m>0)?res:-res;
-	}
-      }
-    }
+    /* Max ULP is 0.524.  */
+    return (m>0)?res:-res;
   }    /*   else  if (k < 0x3fe00000)    */
   /*-------------------- 0.5 <= |x| < 0.75 -----------------------------*/
   else
@@ -135,26 +92,8 @@  __ieee754_asin(double x){
 	   +xx*(asncs.x[n+6]+xx*asncs.x[n+7])))))+asncs.x[n+8];
     t+=p;
     res =asncs.x[n+9] +t;
-    cor = (asncs.x[n+9]-res)+t;
-    if (res == res+1.01*cor) return (m>0)?res:-res;
-    else {
-      r=asncs.x[n+9]+xx*asncs.x[n+10];
-      t=((asncs.x[n+9]-r)+xx*asncs.x[n+10])+(p+xx*asncs.x[n+11]);
-      res = r+t;
-      cor = (r-res)+t;
-      if (res == res+1.0005*cor) return (m>0)?res:-res;
-      else {
-	res1=res+1.1*cor;
-	z=0.5*(res1-res);
-	__dubsin(res,z,w);
-	z=(w[0]-fabs(x))+w[1];
-	if (z>1.0e-27) return (m>0)?min(res,res1):-min(res,res1);
-	else if (z<-1.0e-27) return (m>0)?max(res,res1):-max(res,res1);
-	else {
-	  return (m>0)?res:-res;
-	}
-      }
-    }
+    /* Max ULP is 0.505.  */
+    return (m>0)?res:-res;
   }    /*   else  if (k < 0x3fe80000)    */
   /*--------------------- 0.75 <= |x|< 0.921875 ----------------------*/
   else
@@ -167,28 +106,8 @@  __ieee754_asin(double x){
      +xx*(asncs.x[n+6]+xx*(asncs.x[n+7]+xx*asncs.x[n+8]))))))+asncs.x[n+9];
     t+=p;
     res =asncs.x[n+10] +t;
-    cor = (asncs.x[n+10]-res)+t;
-    if (res == res+1.01*cor) return (m>0)?res:-res;
-    else {
-      r=asncs.x[n+10]+xx*asncs.x[n+11];
-      t=((asncs.x[n+10]-r)+xx*asncs.x[n+11])+(p+xx*asncs.x[n+12]);
-      res = r+t;
-      cor = (r-res)+t;
-      if (res == res+1.0008*cor) return (m>0)?res:-res;
-      else {
-	res1=res+1.1*cor;
-	z=0.5*(res1-res);
-	y=hp0.x-res;
-	z=((hp0.x-y)-res)+(hp1.x-z);
-	__dubcos(y,z,w);
-	z=(w[0]-fabs(x))+w[1];
-	if (z>1.0e-27) return (m>0)?min(res,res1):-min(res,res1);
-	else if (z<-1.0e-27) return (m>0)?max(res,res1):-max(res,res1);
-	else {
-	  return (m>0)?res:-res;
-	}
-      }
-    }
+    /* Max ULP is 0.505.  */
+    return (m>0)?res:-res;
   }    /*   else  if (k < 0x3fed8000)    */
   /*-------------------0.921875 <= |x| < 0.953125 ------------------------*/
   else
@@ -203,29 +122,8 @@  __ieee754_asin(double x){
 		      xx*asncs.x[n+9])))))))+asncs.x[n+10];
     t+=p;
     res =asncs.x[n+11] +t;
-    cor = (asncs.x[n+11]-res)+t;
-    if (res == res+1.01*cor) return (m>0)?res:-res;
-    else {
-      r=asncs.x[n+11]+xx*asncs.x[n+12];
-      t=((asncs.x[n+11]-r)+xx*asncs.x[n+12])+(p+xx*asncs.x[n+13]);
-      res = r+t;
-      cor = (r-res)+t;
-      if (res == res+1.0007*cor) return (m>0)?res:-res;
-      else {
-	res1=res+1.1*cor;
-	z=0.5*(res1-res);
-	y=(hp0.x-res)-z;
-	z=y+hp1.x;
-	y=(y-z)+hp1.x;
-	__dubcos(z,y,w);
-	z=(w[0]-fabs(x))+w[1];
-	if (z>1.0e-27) return (m>0)?min(res,res1):-min(res,res1);
-	else if (z<-1.0e-27) return (m>0)?max(res,res1):-max(res,res1);
-	else {
-	  return (m>0)?res:-res;
-	}
-      }
-    }
+    /* Max ULP is 0.505.  */
+    return (m>0)?res:-res;
   }    /*   else  if (k < 0x3fee8000)    */
 
   /*--------------------0.953125 <= |x| < 0.96875 ------------------------*/
@@ -241,29 +139,8 @@  __ieee754_asin(double x){
 		    xx*(asncs.x[n+9]+xx*asncs.x[n+10]))))))))+asncs.x[n+11];
     t+=p;
     res =asncs.x[n+12] +t;
-    cor = (asncs.x[n+12]-res)+t;
-    if (res == res+1.01*cor) return (m>0)?res:-res;
-    else {
-      r=asncs.x[n+12]+xx*asncs.x[n+13];
-      t=((asncs.x[n+12]-r)+xx*asncs.x[n+13])+(p+xx*asncs.x[n+14]);
-      res = r+t;
-      cor = (r-res)+t;
-      if (res == res+1.0007*cor) return (m>0)?res:-res;
-      else {
-	res1=res+1.1*cor;
-	z=0.5*(res1-res);
-	y=(hp0.x-res)-z;
-	z=y+hp1.x;
-	y=(y-z)+hp1.x;
-	__dubcos(z,y,w);
-	z=(w[0]-fabs(x))+w[1];
-	if (z>1.0e-27) return (m>0)?min(res,res1):-min(res,res1);
-	else if (z<-1.0e-27) return (m>0)?max(res,res1):-max(res,res1);
-	else {
-	  return (m>0)?res:-res;
-	}
-      }
-    }
+    /* Max ULP is 0.505.  */
+    return (m>0)?res:-res;
   }    /*   else  if (k < 0x3fef0000)    */
   /*--------------------0.96875 <= |x| < 1 --------------------------------*/
   else
@@ -282,16 +159,8 @@  __ieee754_asin(double x){
     cor = (hp1.x - 2.0*cc)-2.0*(y+cc)*p;
     res1 = hp0.x - 2.0*y;
     res =res1 + cor;
-    if (res == res+1.003*((res1-res)+cor)) return (m>0)?res:-res;
-    else {
-      c=y+cc;
-      cc=(y-c)+cc;
-      __doasin(c,cc,w);
-      res1=hp0.x-2.0*w[0];
-      cor=((hp0.x-res1)-2.0*w[0])+(hp1.x-2.0*w[1]);
-      res = res1+cor;
-      return (m>0)?res:-res;
-    }
+    /* Max ULP is 0.5015.  */
+    return (m>0)?res:-res;
   }    /*   else  if (k < 0x3ff00000)    */
   /*---------------------------- |x|>=1 -------------------------------*/
   else if (k==0x3ff00000 && u.i[LOW_HALF]==0) return (m>0)?hp0.x:-hp0.x;
@@ -315,11 +184,12 @@  libm_alias_finite (__ieee754_asin, __asin)
 /*                                                                 */
 /*******************************************************************/
 
+/* acos with max ULP of ~0.523 based on random sampling.  */
 double
 SECTION
 __ieee754_acos(double x)
 {
-  double x1,x2,xx,s1,s2,res1,p,t,res,r,cor,cc,y,c,z,w[2],eps;
+  double x2,xx,res1,p,t,res,r,cor,cc,y,c,z;
   mynumber u,v;
   int4 k,m,n;
   u.x = x;
@@ -336,32 +206,8 @@  __ieee754_acos(double x)
     r=hp0.x-x;
     cor=(((hp0.x-r)-x)+hp1.x)-t;
     res = r+cor;
-    cor = (r-res)+cor;
-    if (res == res+1.004*cor) return res;
-    else {
-      x1 = x+big;
-      xx = x*x;
-      x1 -= big;
-      x2 = x - x1;
-      p = x1*x1*x1;
-      s1 = a1.x*p;
-      s2 = ((((((c7*xx + c6)*xx + c5)*xx + c4)*xx + c3)*xx + c2)*xx*xx*x +
-	    ((a1.x+a2.x)*x2*x2+ 0.5*x1*x)*x2) + a2.x*p;
-      res1 = x+s1;
-      s2 = ((x-res1)+s1)+s2;
-      r=hp0.x-res1;
-      cor=(((hp0.x-r)-res1)+hp1.x)-s2;
-      res = r+cor;
-      cor = (r-res)+cor;
-      if (res == res+1.00004*cor) return res;
-      else {
-	__doasin(x,0,w);
-	r=hp0.x-w[0];
-	cor=((hp0.x-r)-w[0])+(hp1.x-w[1]);
-	res=r+cor;
-	return res;
-      }
-    }
+    /* Max ULP is 0.502.  */
+    return res;
   }    /*   else  if (k < 0x3fc00000)    */
   /*----------------------  0.125 <= |x| < 0.5 --------------------*/
   else
@@ -377,35 +223,16 @@  __ieee754_acos(double x)
     y = (m>0)?(hp0.x-asncs.x[n+8]):(hp0.x+asncs.x[n+8]);
     t = (m>0)?(hp1.x-t):(hp1.x+t);
     res = y+t;
-    if (res == res+1.02*((y-res)+t)) return res;
-    else {
-      r=asncs.x[n+8]+xx*asncs.x[n+9];
-      t=((asncs.x[n+8]-r)+xx*asncs.x[n+9])+(p+xx*asncs.x[n+10]);
-      if (m>0)
-	{p = hp0.x-r; t = (((hp0.x-p)-r)-t)+hp1.x; }
-      else
-	{p = hp0.x+r; t = ((hp0.x-p)+r)+(hp1.x+t); }
-      res = p+t;
-      cor = (p-res)+t;
-      if (res == (res+1.0002*cor)) return res;
-      else {
-	res1=res+1.1*cor;
-	z=0.5*(res1-res);
-	__docos(res,z,w);
-	z=(w[0]-x)+w[1];
-	if (z>1.0e-27) return max(res,res1);
-	else if (z<-1.0e-27) return min(res,res1);
-	else return res;
-      }
-    }
+   /* Max ULP is 0.51.  */
+    return res;
   }    /*   else  if (k < 0x3fe00000)    */
 
   /*--------------------------- 0.5 <= |x| < 0.75 ---------------------*/
   else
   if (k < 0x3fe80000) {
     n = 1056+((k&0x000fe000)>>11)*3;
-    if (m>0) {xx = x - asncs.x[n]; eps=1.04; }
-    else {xx = -x - asncs.x[n]; eps=1.02; }
+    if (m>0) {xx = x - asncs.x[n]; }
+    else {xx = -x - asncs.x[n]; }
     t = asncs.x[n+1]*xx;
     p=xx*xx*(asncs.x[n+2]+xx*(asncs.x[n+3]+xx*(asncs.x[n+4]+
 		   xx*(asncs.x[n+5]+xx*(asncs.x[n+6]+
@@ -414,33 +241,16 @@  __ieee754_acos(double x)
    y = (m>0)?(hp0.x-asncs.x[n+9]):(hp0.x+asncs.x[n+9]);
    t = (m>0)?(hp1.x-t):(hp1.x+t);
    res = y+t;
-   if (res == res+eps*((y-res)+t)) return res;
-   else {
-     r=asncs.x[n+9]+xx*asncs.x[n+10];
-     t=((asncs.x[n+9]-r)+xx*asncs.x[n+10])+(p+xx*asncs.x[n+11]);
-     if (m>0) {p = hp0.x-r; t = (((hp0.x-p)-r)-t)+hp1.x; eps=1.0004; }
-     else   {p = hp0.x+r; t = ((hp0.x-p)+r)+(hp1.x+t); eps=1.0002; }
-     res = p+t;
-     cor = (p-res)+t;
-     if (res == (res+eps*cor)) return res;
-     else {
-       res1=res+1.1*cor;
-       z=0.5*(res1-res);
-       __docos(res,z,w);
-       z=(w[0]-x)+w[1];
-       if (z>1.0e-27) return max(res,res1);
-       else if (z<-1.0e-27) return min(res,res1);
-       else return res;
-     }
-   }
+   /* Max ULP is 0.523 based on random sampling.  */
+   return res;
   }    /*   else  if (k < 0x3fe80000)    */
 
 /*------------------------- 0.75 <= |x| < 0.921875 -------------*/
   else
   if (k < 0x3fed8000) {
     n = 992+((k&0x000fe000)>>13)*13;
-    if (m>0) {xx = x - asncs.x[n]; eps = 1.04; }
-    else {xx = -x - asncs.x[n]; eps = 1.01; }
+    if (m>0) {xx = x - asncs.x[n]; }
+    else {xx = -x - asncs.x[n]; }
     t = asncs.x[n+1]*xx;
     p=xx*xx*(asncs.x[n+2]+xx*(asncs.x[n+3]+xx*(asncs.x[n+4]+
 		      xx*(asncs.x[n+5]+xx*(asncs.x[n+6]+xx*(asncs.x[n+7]+
@@ -449,33 +259,16 @@  __ieee754_acos(double x)
     y = (m>0)?(hp0.x-asncs.x[n+10]):(hp0.x+asncs.x[n+10]);
     t = (m>0)?(hp1.x-t):(hp1.x+t);
     res = y+t;
-    if (res == res+eps*((y-res)+t)) return res;
-    else {
-      r=asncs.x[n+10]+xx*asncs.x[n+11];
-      t=((asncs.x[n+10]-r)+xx*asncs.x[n+11])+(p+xx*asncs.x[n+12]);
-      if (m>0) {p = hp0.x-r; t = (((hp0.x-p)-r)-t)+hp1.x; eps=1.0032; }
-      else   {p = hp0.x+r; t = ((hp0.x-p)+r)+(hp1.x+t); eps=1.0008; }
-      res = p+t;
-      cor = (p-res)+t;
-      if (res == (res+eps*cor)) return res;
-      else {
-	res1=res+1.1*cor;
-	z=0.5*(res1-res);
-	__docos(res,z,w);
-	z=(w[0]-x)+w[1];
-	if (z>1.0e-27) return max(res,res1);
-	else if (z<-1.0e-27) return min(res,res1);
-	else return res;
-      }
-    }
+   /* Max ULP is 0.523 based on random sampling.  */
+    return res;
   }    /*   else  if (k < 0x3fed8000)    */
 
 /*-------------------0.921875 <= |x| < 0.953125 ------------------*/
   else
   if (k < 0x3fee8000) {
     n = 884+((k&0x000fe000)>>13)*14;
-    if (m>0) {xx = x - asncs.x[n]; eps=1.04; }
-    else {xx = -x - asncs.x[n]; eps =1.005; }
+    if (m>0) {xx = x - asncs.x[n]; }
+    else {xx = -x - asncs.x[n]; }
     t = asncs.x[n+1]*xx;
     p=xx*xx*(asncs.x[n+2]+xx*(asncs.x[n+3]+xx*(asncs.x[n+4]+
 		   xx*(asncs.x[n+5]+xx*(asncs.x[n+6]
@@ -485,33 +278,16 @@  __ieee754_acos(double x)
     y = (m>0)?(hp0.x-asncs.x[n+11]):(hp0.x+asncs.x[n+11]);
     t = (m>0)?(hp1.x-t):(hp1.x+t);
     res = y+t;
-    if (res == res+eps*((y-res)+t)) return res;
-    else {
-      r=asncs.x[n+11]+xx*asncs.x[n+12];
-      t=((asncs.x[n+11]-r)+xx*asncs.x[n+12])+(p+xx*asncs.x[n+13]);
-      if (m>0) {p = hp0.x-r; t = (((hp0.x-p)-r)-t)+hp1.x; eps=1.0030; }
-      else   {p = hp0.x+r; t = ((hp0.x-p)+r)+(hp1.x+t); eps=1.0005; }
-      res = p+t;
-      cor = (p-res)+t;
-      if (res == (res+eps*cor)) return res;
-      else {
-	res1=res+1.1*cor;
-	z=0.5*(res1-res);
-	__docos(res,z,w);
-	z=(w[0]-x)+w[1];
-	if (z>1.0e-27) return max(res,res1);
-	else if (z<-1.0e-27) return min(res,res1);
-	else return res;
-      }
-    }
+   /* Max ULP is 0.523 based on random sampling.  */
+    return res;
   }    /*   else  if (k < 0x3fee8000)    */
 
   /*--------------------0.953125 <= |x| < 0.96875 ----------------*/
   else
   if (k < 0x3fef0000) {
     n = 768+((k&0x000fe000)>>13)*15;
-    if (m>0) {xx = x - asncs.x[n]; eps=1.04; }
-    else {xx = -x - asncs.x[n]; eps=1.005;}
+    if (m>0) {xx = x - asncs.x[n]; }
+    else {xx = -x - asncs.x[n]; }
     t = asncs.x[n+1]*xx;
     p=xx*xx*(asncs.x[n+2]+xx*(asncs.x[n+3]+xx*(asncs.x[n+4]+
 	    xx*(asncs.x[n+5]+xx*(asncs.x[n+6]
@@ -521,25 +297,8 @@  __ieee754_acos(double x)
     y = (m>0)?(hp0.x-asncs.x[n+12]):(hp0.x+asncs.x[n+12]);
    t = (m>0)?(hp1.x-t):(hp1.x+t);
    res = y+t;
-   if (res == res+eps*((y-res)+t)) return res;
-   else {
-     r=asncs.x[n+12]+xx*asncs.x[n+13];
-     t=((asncs.x[n+12]-r)+xx*asncs.x[n+13])+(p+xx*asncs.x[n+14]);
-     if (m>0) {p = hp0.x-r; t = (((hp0.x-p)-r)-t)+hp1.x; eps=1.0030; }
-     else   {p = hp0.x+r; t = ((hp0.x-p)+r)+(hp1.x+t); eps=1.0005; }
-     res = p+t;
-     cor = (p-res)+t;
-     if (res == (res+eps*cor)) return res;
-     else {
-       res1=res+1.1*cor;
-       z=0.5*(res1-res);
-       __docos(res,z,w);
-       z=(w[0]-x)+w[1];
-       if (z>1.0e-27) return max(res,res1);
-       else if (z<-1.0e-27) return min(res,res1);
-       else return res;
-     }
-   }
+   /* Max ULP is 0.523 based on random sampling.  */
+   return res;
   }    /*   else  if (k < 0x3fef0000)    */
   /*-----------------0.96875 <= |x| < 1 ---------------------------*/
 
@@ -560,28 +319,14 @@  __ieee754_acos(double x)
       cor = (hp1.x - cc)-(y+cc)*p;
       res1 = hp0.x - y;
       res =res1 + cor;
-      if (res == res+1.002*((res1-res)+cor)) return (res+res);
-      else {
-	c=y+cc;
-	cc=(y-c)+cc;
-	__doasin(c,cc,w);
-	res1=hp0.x-w[0];
-	cor=((hp0.x-res1)-w[0])+(hp1.x-w[1]);
-	res = res1+cor;
-	return (res+res);
-      }
+      /* Max ULP is 0.501.  */
+      return (res+res);
     }
     else {
       cor = cc+p*(y+cc);
       res = y + cor;
-      if (res == res+1.03*((y-res)+cor)) return (res+res);
-      else {
-	c=y+cc;
-	cc=(y-c)+cc;
-	__doasin(c,cc,w);
-	res = w[0];
-	return (res+res);
-      }
+      /* Max ULP is 0.515.  */
+      return (res+res);
     }
   }    /*   else  if (k < 0x3ff00000)    */