1 files changed, 76 insertions, 0 deletions
diff --git a/2.3-1/src/c/linearAlgebra/givens/dgivensa.c b/2.3-1/src/c/linearAlgebra/givens/dgivensa.c
new file mode 100644
index 00000000..9bf0637b
--- /dev/null
+++ b/2.3-1/src/c/linearAlgebra/givens/dgivensa.c
@@ -0,0 +1,76 @@
+/* Copyright (C) 2017 - 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: Sandeep Gupta
+ Organization: FOSSEE, IIT Bombay
+ Email: toolbox@scilab.in
+ */
+
+/*  GIVENS scilab function
+	Syntax : u=givens(xy)
+    u=givens(x,y)
+    xy = [x;y], u=givens(xy)
+	returns a 2*2 matrix u such that u*xy=[r;0].
+	c is equal to u*xy
+	givens(x,y)=givens([x;y])
+*/
+
+#include "givens.h"
+#include <stdio.h>
+#include <math.h>
+#include "norm.h"
+
+/* All variable names are according to scilab code */
+
+void dgivensa(int ninp,double *inp1,int row,int col,double *inp2,int row1,int col1,int nout,double *out1,double *out2){
+	double *x;	
+	double r;
+	x = (double *)malloc((double)2*sizeof(double));
+	if(ninp == 2){
+		if(row != 1 || col != 1 || row1 != 1 || col1 != 1){
+			printf("Wrong size for input argument: A column vector expected.\n");
+			return;		
+		}
+		*(x) = *(inp1);
+		*(x+1) = *(inp2);
+	}
+	else{
+		//printf("(%d %d)",row,col);
+		if(row != 2 || col != 1){
+			printf("Wrong size for input argument: A column vector expected.\n");						
+			return;		
+		}
+		//printf("(%lf %lf)",inp1[0],inp1[1]);		
+		x[0] = inp1[0];
+		x[1] = inp1[1];	
+	}
+	if(*(x+1) != 0){
+		//printf("(%lf %lf)",x[0],x[1]);
+		/*Norm of type 2 - find the maximum singular value*/
+		r = dnorma(x,2,1,2);
+		//printf("%lf \n",r);	
+		*(out1) = (*(x))/r;
+		*(out1+1) = -(*(x+1))/r;
+		*(out1+2) = (*(x+1))/r;
+		*(out1+3) = (*(x))/r;
+		if(nout == 2){
+			*(out2) = r;
+			*(out2+1) = 0;		
+		}
+		
+	}	
+	else{
+		*(out1) = 1;
+		*(out1+1) = 0;
+		*(out1+2) = 1;
+		*(out1+3) = 0;		
+		if(nout == 2){
+			*(out2) = *(x);
+			*(out2+1) = *(x+1);
+		}		
+	}
+}