first commit of the new libm!

[musl] / src / math / __log1pf.h

diff --git a/src/math/__log1pf.h b/src/math/__log1pf.h
new file mode 100644 (file)
index 0000000..110acec
--- /dev/null
+++ b/src/math/__log1pf.h
@@ -0,0 +1,35 @@
+/* origin: FreeBSD /usr/src/lib/msun/src/k_logf.h */
+/*
+ * ====================================================
+ * 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.
+ * ====================================================
+ */
+/*
+ * See comments in __log1p.h.
+ */
+
+/* |(log(1+s)-log(1-s))/s - Lg(s)| < 2**-34.24 (~[-4.95e-11, 4.97e-11]). */
+static const float
+Lg1 = 0xaaaaaa.0p-24, /* 0.66666662693 */
+Lg2 = 0xccce13.0p-25, /* 0.40000972152 */
+Lg3 = 0x91e9ee.0p-25, /* 0.28498786688 */
+Lg4 = 0xf89e26.0p-26; /* 0.24279078841 */
+
+static inline float __log1pf(float f)
+{
+       float hfsq,s,z,R,w,t1,t2;
+
+       s = f/((float)2.0+f);
+       z = s*s;
+       w = z*z;
+       t1 = w*(Lg2+w*Lg4);
+       t2 = z*(Lg1+w*Lg3);
+       R = t2+t1;
+       hfsq = (float)0.5*f*f;
+       return s*(hfsq+R);
+}