* device/lib/pic/libm: NEW, added math library functions

[fw/sdcc] / device / lib / pic / libm / tancotf.c

diff --git a/device/lib/pic/libm/tancotf.c b/device/lib/pic/libm/tancotf.c
new file mode 100644 (file)
index 0000000..60e3ada
--- /dev/null
+++ b/device/lib/pic/libm/tancotf.c
@@ -0,0 +1,89 @@
+/*  tancotf.c: Computes tan or cot of a 32-bit float as outlined in [1]
+
+    Copyright (C) 2001, 2002  Jesus Calvino-Fraga, jesusc@ieee.org 
+
+    This library 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 2.1 of the License, or (at your option) any later version.
+
+    This library 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
+    Lesser General Public License for more details.
+
+    You should have received a copy of the GNU Lesser General Public
+    License along with this library; if not, write to the Free Software
+    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA */
+
+/* [1] William James Cody and W.  M.  Waite.  _Software manual for the
+   elementary functions_, Englewood Cliffs, N.J.:Prentice-Hall, 1980. */
+
+/* Version 1.0 - Initial release */
+
+/*
+** $Id: tancotf.c 3654 2005-01-24 10:38:53Z vrokas $
+*/
+
+#include <math.h>
+#include <errno.h>
+
+#define P0  0.100000000E+1
+#define P1 -0.958017723E-1
+#define Q0  0.100000000E+1
+#define Q1 -0.429135777E+0
+#define Q2  0.971685835E-2
+
+#define C1  1.5703125
+#define C2  4.83826794897E-4
+
+#define P(f,g) (P1*g*f+f)
+#define Q(g) ((Q2*g+Q1)*g+Q0)
+
+//A reasonable choice for YMAX is the integer part of B**(t/2)*PI/2:
+#define YMAX 6433.0
+
+float tancotf(const float x, const int iscotan)
+{
+    float f, g, xn, xnum, xden;
+    int n;
+
+    if (fabsf(x) > YMAX)
+    {
+        errno = ERANGE;
+        return 0.0;
+    }
+
+    /*Round x*2*PI to the nearest integer*/
+    n=(x*TWO_O_PI+(x>0.0?0.5:-0.5)); /*works for +-x*/
+    xn=n;
+
+    xnum=(int)x;
+    xden=x-xnum;
+    f=((xnum-xn*C1)+xden)-xn*C2;
+
+    if (fabsf(f) < EPS)
+    {
+        xnum = f;
+        xden = 1.0;
+    }
+    else
+    {
+        g = f*f;
+        xnum = P(f,g);
+        xden = Q(g);
+    }
+
+    if(n&1)
+    //xn is odd
+    {
+        if(iscotan) return (-xnum/xden);
+               else return (-xden/xnum);
+    }
+    else
+    {
+        if(iscotan) return (xden/xnum);
+               else return (xnum/xden);
+    }
+}
+