Index: fusl/src/math/__tandf.c |
diff --git a/fusl/src/math/__tandf.c b/fusl/src/math/__tandf.c |
new file mode 100644 |
index 0000000000000000000000000000000000000000..25047eeee9c098894010a3984372ba63cb698656 |
--- /dev/null |
+++ b/fusl/src/math/__tandf.c |
@@ -0,0 +1,54 @@ |
+/* origin: FreeBSD /usr/src/lib/msun/src/k_tanf.c */ |
+/* |
+ * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com. |
+ * Optimized by Bruce D. Evans. |
+ */ |
+/* |
+ * ==================================================== |
+ * Copyright 2004 Sun Microsystems, Inc. All Rights Reserved. |
+ * |
+ * Permission to use, copy, modify, and distribute this |
+ * software is freely granted, provided that this notice |
+ * is preserved. |
+ * ==================================================== |
+ */ |
+ |
+#include "libm.h" |
+ |
+/* |tan(x)/x - t(x)| < 2**-25.5 (~[-2e-08, 2e-08]). */ |
+static const double T[] = { |
+ 0x15554d3418c99f.0p-54, /* 0.333331395030791399758 */ |
+ 0x1112fd38999f72.0p-55, /* 0.133392002712976742718 */ |
+ 0x1b54c91d865afe.0p-57, /* 0.0533812378445670393523 */ |
+ 0x191df3908c33ce.0p-58, /* 0.0245283181166547278873 */ |
+ 0x185dadfcecf44e.0p-61, /* 0.00297435743359967304927 */ |
+ 0x1362b9bf971bcd.0p-59, /* 0.00946564784943673166728 */ |
+}; |
+ |
+float __tandf(double x, int odd) |
+{ |
+ double_t z,r,w,s,t,u; |
+ |
+ z = x*x; |
+ /* |
+ * Split up the polynomial into small independent terms to give |
+ * opportunities for parallel evaluation. The chosen splitting is |
+ * micro-optimized for Athlons (XP, X64). It costs 2 multiplications |
+ * relative to Horner's method on sequential machines. |
+ * |
+ * We add the small terms from lowest degree up for efficiency on |
+ * non-sequential machines (the lowest degree terms tend to be ready |
+ * earlier). Apart from this, we don't care about order of |
+ * operations, and don't need to to care since we have precision to |
+ * spare. However, the chosen splitting is good for accuracy too, |
+ * and would give results as accurate as Horner's method if the |
+ * small terms were added from highest degree down. |
+ */ |
+ r = T[4] + z*T[5]; |
+ t = T[2] + z*T[3]; |
+ w = z*z; |
+ s = z*x; |
+ u = T[0] + z*T[1]; |
+ r = (x + s*u) + (s*w)*(t + w*r); |
+ return odd ? -1.0/r : r; |
+} |