1 files changed, 59 insertions, 0 deletions
diff --git a/sysdeps/ieee754/dbl-64/mptan.c b/sysdeps/ieee754/dbl-64/mptan.c
new file mode 100644
index 0000000000..6a9c85e958
--- /dev/null
+++ b/sysdeps/ieee754/dbl-64/mptan.c
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+
+/*
+ * IBM Accurate Mathematical Library
+ * Copyright (c) International Business Machines Corp., 2001
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or 
+ * (at your option) any later version.
+ * 
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  
+ */
+/**********************************************************************/
+/* MODULE_NAME:mptan.c                                                */
+/*                                                                    */
+/* FUNCTION: mptan                                                    */
+/*                                                                    */
+/* FILES NEEDED: endian.h  mpa.h                                      */
+/*               mpa.c  sincos32.c branred.c                          */
+/*                                                                    */
+/* Multi-Precision tan() function subroutine, for p=32.  It is based  */
+/* on the routines mpranred() and c32(). mpranred() performs range    */
+/* reduction of a double number x into a multiple precision number    */
+/* y, such that y=x-n*pi/2, abs(y)<pi/4, n=0,+-1,+-2,....  c32()      */
+/* computes both sin(y), cos(y).  tan(x) is either sin(y)/cos(y)      */
+/* or -cos(y)/sin(y). The precision of the result is of about 559     */
+/* significant bits.                                                  */
+/*                                                                    */
+/**********************************************************************/
+#include "endian.h"
+#include "mpa.h"
+
+int mpranred(double, mp_no *, int);
+void c32(mp_no *, mp_no *, mp_no *, int);
+
+void mptan(double x, mp_no *mpy, int p) {
+
+  static const double MONE = -1.0;
+
+  int n;
+  mp_no mpw, mpc, mps;
+
+  n = mpranred(x, &mpw, p) & 0x00000001; /* negative or positive result */
+  c32(&mpw, &mpc, &mps, p);              /* computing sin(x) and cos(x) */
+  if (n)                     /* second or fourth quarter of unit circle */
+  { dvd(&mpc,&mps,mpy,p);
+    mpy->d[0] *= MONE;
+  }                          /* tan is negative in this area */
+  else  dvd(&mps,&mpc,mpy,p);
+
+  return;
+}