Implement missing Math Inverse Hyperbolic functions (#3675)

Math.acosh, Math.asinh, Math.acosh C implementation ported from fdlibm Part of Issue #3568 JerryScript-DCO-1.0-Signed-off-by: Rafal Walczyna r.walczyna@samsung.com
2020-04-20 15:41:06 +02:00
parent 453da11398
commit 9c7a699d10
11 changed files with 554 additions and 12 deletions
@@ -0,0 +1,92 @@
+/* Copyright JS Foundation and other contributors, http://js.foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ * This file is based on work under the following copyright and permission
+ * notice:
+ *
+ *     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.
+ *
+ *     @(#)e_acosh.c 1.3 95/01/18
+ */
+
+#include "jerry-libm-internal.h"
+
+/* 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.
+ */
+
+#define one 1.0
+#define ln2 6.93147180559945286227e-01 /* 0x3FE62E42, 0xFEFA39EF */
+
+double
+acosh (double x)
+{
+  double t;
+  int hx;
+  hx = __HI (x);
+  if (hx < 0x3ff00000)
+  {
+    /* x < 1 */
+    return NAN;
+  }
+  else if (hx >= 0x41b00000)
+  {
+    /* x > 2**28 */
+    if (hx >= 0x7ff00000)
+    {
+      /* x is inf of NaN */
+      return x + x;
+    }
+    else
+    {
+      /* acosh(huge) = log(2x) */
+      return log (x) + ln2;
+    }
+  }
+  else if (((hx - 0x3ff00000) | __LO (x)) == 0)
+  {
+    /* acosh(1) = 0 */
+    return 0.0;
+  }
+  else if (hx > 0x40000000)
+  {
+    /* 2**28 > x > 2 */
+    t = x * x;
+    return 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));
+  }
+} /* acosh */
+
+#undef one
+#undef ln2