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-rw-r--r--modules/fdlibm/src/k_logf.h39
1 files changed, 39 insertions, 0 deletions
diff --git a/modules/fdlibm/src/k_logf.h b/modules/fdlibm/src/k_logf.h
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+++ b/modules/fdlibm/src/k_logf.h
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+/*
+ * ====================================================
+ * 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.
+ * ====================================================
+ */
+
+//#include <sys/cdefs.h>
+//__FBSDID("$FreeBSD$");
+
+/*
+ * Float version of k_log.h. See the latter for most comments.
+ */
+
+static const float
+/* |(log(1+s)-log(1-s))/s - Lg(s)| < 2**-34.24 (~[-4.95e-11, 4.97e-11]). */
+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
+k_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);
+}