1 files changed, 49 insertions, 0 deletions
diff --git a/2.3-1/src/c/specialFunctions/erfinv/derfinvs.c b/2.3-1/src/c/specialFunctions/erfinv/derfinvs.c
new file mode 100644
index 00000000..379d6af5
--- /dev/null
+++ b/2.3-1/src/c/specialFunctions/erfinv/derfinvs.c
@@ -0,0 +1,49 @@
+/* Copyright (C) 2016 - IIT Bombay - FOSSEE
+
+ This file must be used under the terms of the CeCILL.
+ This source file is licensed as described in the file COPYING, which
+ you should have received as part of this distribution.  The terms
+ are also available at
+ http://www.cecill.info/licences/Licence_CeCILL_V2-en.txt
+ Author: Brijesh Gupta C R
+ Organization: FOSSEE, IIT Bombay
+ Email: toolbox@scilab.in
+*/
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <math.h>
+#include "erfinv.h"
+
+# define PI 3.1415927
+
+double derfinvs (double inp1)
+{
+    double a[] = {0.88622692374517353,-1.6601283962374516,0.92661860147244357,-0.14110320437680104};
+    double b[] = {-2.13505380615258078,1.46060340345661088,-0.33198239813321595,0.01197270616590528};
+    double c[] = {-1.994216456587148,-1.87267416351196,3.60874665878559364,1.82365845766309853};
+    double d[] = {3.74146294065960872,1.81848952562894617};
+
+    if ((inp1 > 1) || (inp1 < -1))
+    {
+	return 0.0/0.0;
+    }    
+    if ((inp1 >= -0.7) && (inp1 <= 0.7))
+    {
+        double sq = inp1 * inp1;
+        return (inp1 * (((a[3]*sq+a[2]) * sq+a[1]) * sq+a[0]) /  ((((b[3]*sq+b[2]) * sq+b[1]) * sq+b[0]) * sq+1));
+    }
+
+    else if ((inp1 > 0.7) && (inp1 < 1))
+    {
+        double z = sqrt(-log((1-inp1)/2));
+        return ((((c[3]*z+c[2]) * z+c[1]) * z+c[0]) / ((d[1]*z+d[0]) * z+1));
+    }
+
+    else if ((inp1 > -1) && (inp1 < 0.7))
+    {
+        double z = sqrt(-log((1+inp1)/2));
+        return (-(((c[3]*z+c[2]) * z+c[1]) * z+c[0]) / ((d[1]*z+d[0]) * z+1));
+    }
+}
+