auto import from //depot/cupcake/@135843
diff --git a/libm/src/e_acosh.c b/libm/src/e_acosh.c
new file mode 100644
index 0000000..ccb1521
--- /dev/null
+++ b/libm/src/e_acosh.c
@@ -0,0 +1,63 @@
+
+/* @(#)e_acosh.c 1.3 95/01/18 */
+/*
+ * ====================================================
+ * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
+ *
+ * Developed at SunSoft, a Sun Microsystems, Inc. business.
+ * Permission to use, copy, modify, and distribute this
+ * software is freely granted, provided that this notice
+ * is preserved.
+ * ====================================================
+ *
+ */
+
+#ifndef lint
+static char rcsid[] = "$FreeBSD: src/lib/msun/src/e_acosh.c,v 1.8 2005/02/04 18:26:05 das Exp $";
+#endif
+
+/* __ieee754_acosh(x)
+ * Method :
+ * Based on
+ * acosh(x) = log [ x + sqrt(x*x-1) ]
+ * we have
+ * acosh(x) := log(x)+ln2, if x is large; else
+ * acosh(x) := log(2x-1/(sqrt(x*x-1)+x)) if x>2; else
+ * acosh(x) := log1p(t+sqrt(2.0*t+t*t)); where t=x-1.
+ *
+ * Special cases:
+ * acosh(x) is NaN with signal if x<1.
+ * acosh(NaN) is NaN without signal.
+ */
+
+#include "math.h"
+#include "math_private.h"
+
+static const double
+one = 1.0,
+ln2 = 6.93147180559945286227e-01; /* 0x3FE62E42, 0xFEFA39EF */
+
+double
+__ieee754_acosh(double x)
+{
+ double t;
+ int32_t hx;
+ u_int32_t lx;
+ EXTRACT_WORDS(hx,lx,x);
+ if(hx<0x3ff00000) { /* x < 1 */
+ return (x-x)/(x-x);
+ } else if(hx >=0x41b00000) { /* x > 2**28 */
+ if(hx >=0x7ff00000) { /* x is inf of NaN */
+ return x+x;
+ } else
+ return __ieee754_log(x)+ln2; /* acosh(huge)=log(2x) */
+ } else if(((hx-0x3ff00000)|lx)==0) {
+ return 0.0; /* acosh(1) = 0 */
+ } else if (hx > 0x40000000) { /* 2**28 > x > 2 */
+ t=x*x;
+ return __ieee754_log(2.0*x-one/(x+sqrt(t-one)));
+ } else { /* 1<x<2 */
+ t = x-one;
+ return log1p(t+sqrt(2.0*t+t*t));
+ }
+}