diff libquadmath/math/cosq.c @ 68:561a7518be6b

update gcc-4.6
author Nobuyasu Oshiro <dimolto@cr.ie.u-ryukyu.ac.jp>
date Sun, 21 Aug 2011 07:07:55 +0900
parents
children 04ced10e8804
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--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/libquadmath/math/cosq.c	Sun Aug 21 07:07:55 2011 +0900
@@ -0,0 +1,82 @@
+/* s_cosl.c -- long double version of s_cos.c.
+ * Conversion to long double by Jakub Jelinek, jj@ultra.linux.cz.
+ */
+
+/*
+ * ====================================================
+ * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
+ *
+ * Developed at SunPro, a Sun Microsystems, Inc. business.
+ * Permission to use, copy, modify, and distribute this
+ * software is freely granted, provided that this notice
+ * is preserved.
+ * ====================================================
+ */
+
+/* cosl(x)
+ * Return cosine function of x.
+ *
+ * kernel function:
+ *	__kernel_sinl		... sine function on [-pi/4,pi/4]
+ *	__kernel_cosl		... cosine function on [-pi/4,pi/4]
+ *	__ieee754_rem_pio2l	... argument reduction routine
+ *
+ * Method.
+ *      Let S,C and T denote the sin, cos and tan respectively on
+ *	[-PI/4, +PI/4]. Reduce the argument x to y1+y2 = x-k*pi/2
+ *	in [-pi/4 , +pi/4], and let n = k mod 4.
+ *	We have
+ *
+ *          n        sin(x)      cos(x)        tan(x)
+ *     ----------------------------------------------------------
+ *	    0	       S	   C		 T
+ *	    1	       C	  -S		-1/T
+ *	    2	      -S	  -C		 T
+ *	    3	      -C	   S		-1/T
+ *     ----------------------------------------------------------
+ *
+ * Special cases:
+ *      Let trig be any of sin, cos, or tan.
+ *      trig(+-INF)  is NaN, with signals;
+ *      trig(NaN)    is that NaN;
+ *
+ * Accuracy:
+ *	TRIG(x) returns trig(x) nearly rounded
+ */
+
+#include "quadmath-imp.h"
+
+__float128
+cosq (__float128 x)
+{
+	__float128 y[2],z=0.0Q;
+	int64_t n, ix;
+
+    /* High word of x. */
+	GET_FLT128_MSW64(ix,x);
+
+    /* |x| ~< pi/4 */
+	ix &= 0x7fffffffffffffffLL;
+	if(ix <= 0x3ffe921fb54442d1LL)
+	  return __quadmath_kernel_cosq(x,z);
+
+    /* cos(Inf or NaN) is NaN */
+	else if (ix>=0x7fff000000000000LL) {
+	    if (ix == 0x7fff000000000000LL) {
+		GET_FLT128_LSW64(n,x);
+	    }
+	    return x-x;
+	}
+
+    /* argument reduction needed */
+	else {
+	    n = __quadmath_rem_pio2q(x,y);
+	    switch(n&3) {
+		case 0: return  __quadmath_kernel_cosq(y[0],y[1]);
+		case 1: return -__quadmath_kernel_sinq(y[0],y[1],1);
+		case 2: return -__quadmath_kernel_cosq(y[0],y[1]);
+		default:
+		        return  __quadmath_kernel_sinq(y[0],y[1],1);
+	    }
+	}
+}