For small arguments, these functions use simple approximations,

e.g. cos(small) = 1, sin(small) = small.  This commit tightens
the thresholds at which the simple approximations are used.

Reviewed by:	bde

lib/msun/src/e_asin.c

@@ -82,7 +82,7 @@ __ieee754_asin(double x)
 		return x*pio2_hi+x*pio2_lo;	
 	    return (x-x)/(x-x);		/* asin(|x|>1) is NaN */   
 	} else if (ix<0x3fe00000) {	/* |x|<0.5 */
-	    if(ix<0x3e400000) {		/* if |x| < 2**-27 */
+	    if(ix<0x3e500000) {		/* if |x| < 2**-26 */
 		if(huge+x>one) return x;/* return x with inexact if x!=0*/
 	    }
 	    t = x*x;

lib/msun/src/s_atan.c

@@ -87,7 +87,7 @@ atan(double x)
 	    if(hx>0) return  atanhi[3]+*(volatile double *)&atanlo[3];
 	    else     return -atanhi[3]-*(volatile double *)&atanlo[3];
 	} if (ix < 0x3fdc0000) {	/* |x| < 0.4375 */
-	    if (ix < 0x3e200000) {	/* |x| < 2^-29 */
+	    if (ix < 0x3e400000) {	/* |x| < 2^-27 */
 		if(huge+x>one) return x;	/* raise inexact */
 	    }
 	    id = -1;

lib/msun/src/s_cos.c

@@ -63,7 +63,7 @@ cos(double x)
     /* |x| ~< pi/4 */
 	ix &= 0x7fffffff;
 	if(ix <= 0x3fe921fb) {
-	    if(ix<0x3e400000)			/* if x < 2**-27 */
+	    if(ix<0x3e46a09e)			/* if x < 2**-27 * sqrt(2) */
 		if(((int)x)==0) return 1.0;	/* generate inexact */
 	    return __kernel_cos(x,z);
 	}

lib/msun/src/s_sin.c

@@ -63,7 +63,7 @@ sin(double x)
     /* |x| ~< pi/4 */
 	ix &= 0x7fffffff;
 	if(ix <= 0x3fe921fb) {
-	    if(ix<0x3e400000)			/* |x| < 2**-27 */
+	    if(ix<0x3e500000)			/* |x| < 2**-26 */
 	       {if((int)x==0) return x;}	/* generate inexact */
 	    return __kernel_sin(x,z,0);
 	}

lib/msun/src/s_tan.c

@@ -62,7 +62,7 @@ tan(double x)
     /* |x| ~< pi/4 */
 	ix &= 0x7fffffff;
 	if(ix <= 0x3fe921fb) {
-	    if(ix<0x3e300000)			/* x < 2**-28 */
+	    if(ix<0x3e400000)			/* x < 2**-27 */
 		if((int)x==0) return x;		/* generate inexact */
 	    return __kernel_tan(x,z,1);
 	}