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 +1,100 @@
+/* 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_atanh.c 1.3 95/01/18
+ */
+
+#include "jerry-libm-internal.h"
+
+/* atanh(x)
+ * Method :
+ *    1.Reduced x to positive by atanh(-x) = -atanh(x)
+ *    2.For x >= 0.5
+ *              1              2x                          x
+ *  atanh(x) = --- * log(1 + -------) = 0.5 * log1p(2 * --------)
+ *              2             1 - x                      1 - x
+ *
+ *   For x < 0.5
+*    atanh(x) = 0.5 * log1p(2x + 2x * x / (1 - x))
+ *
+ * Special cases:
+ *  atanh(x) is NaN if |x| > 1 with signal;
+ *  atanh(NaN) is that NaN with no signal;
+ *  atanh(+-1) is +-INF with signal.
+ *
+ */
+
+#define zero 0.0
+#define one 1.0
+#define huge 1.0e+300
+
+double
+atanh (double x)
+{
+  double t;
+  int hx, ix;
+  double_accessor temp;
+  temp.dbl = x;
+  hx = temp.as_int.hi;
+  ix = hx & 0x7fffffff;
+
+  /* |x| > 1 */
+  if ((ix | ((unsigned int)(temp.as_int.lo | (-temp.as_int.lo)) >> 31)) > 0x3ff00000)
+  {
+    return NAN;
+  }
+  if (ix == 0x3ff00000)
+  {
+    return x / zero;
+  }
+  if (ix < 0x3e300000 && (huge + x) > zero)
+  {
+    return x; /* x<2**-28 */
+  }
+
+  /* x <- |x| */
+  temp.as_int.hi = ix;
+  if (ix < 0x3fe00000)
+  {
+    /* x < 0.5 */
+    t = temp.dbl + temp.dbl;
+    t = 0.5 * log1p (t + t * temp.dbl / (one - temp.dbl));
+  }
+  else
+  {
+    t = 0.5 * log1p ((temp.dbl + temp.dbl) / (one - temp.dbl));
+  }
+  if (hx >= 0)
+  {
+    return t;
+  }
+  else
+  {
+    return -t;
+  }
+} /* atanh */
+
+#undef zero
+#undef one
+#undef huge