19-June-2017

1 files changed, 113 insertions, 0 deletions

diff --git a/src/c/linearAlgebra/spec2/dspec2a.c b/src/c/linearAlgebra/spec2/dspec2a.c
new file mode 100644
index 0000000..98b2c5a
--- /dev/null
+++ b/src/c/linearAlgebra/spec2/dspec2a.c
@@ -0,0 +1,113 @@
+/*
+ *  Scilab ( http://www.scilab.org/ ) - This file is part of Scilab
+ *  Copyright (C) 2008 - INRIA - Arnaud TORSET
+ *
+ *  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
+ *
+ */
+ 
+#include <stdlib.h>
+#include "spec.h"
+#include "lapack.h"
+#include "zeros.h"
+#include "max.h"
+
+void dspec2a(double* in, int rows,double* eigenvalues,double* eigenvectors){
+	int i=0, j=0, ij=0, ij1=0;
+	int symmetric=0;
+	int INFO=0;
+	int iWorkSize = 0;
+	double* pdblWork;
+	double* outReal;
+	double* outImag;
+	double* pdblLeftvectors;
+	double* pdblRightvectors;
+	double* inCopy;
+	
+	/* FIXME : malloc here */
+	inCopy = (double*)malloc((unsigned int)(rows*rows) * sizeof(double));
+	outReal = (double*)malloc((unsigned int)rows * sizeof(double));
+	outImag = NULL;
+	pdblLeftvectors=NULL;
+	pdblRightvectors=NULL;
+	
+	
+	iWorkSize = 4*rows;
+	pdblWork = (double*)malloc((unsigned int)iWorkSize * sizeof(double));
+	
+	for(i=0;i<rows*rows;i++)	inCopy[i]=in[i];
+	
+	
+	
+	/* look if the matrix is symmetric */
+	for (i=0;i<rows;i++){	
+		for (j=0;j<rows;j++) 	
+			if (in[i*rows+j]!=in[i+j*rows]) break;
+		if (j!=rows) break;
+		
+	}
+	
+	/* the matrix is symmetric if the 2 loops goes to end i.e
+		i==rows and j==rows */
+	if ((i==rows)&&(j==rows)) symmetric=1;
+	
+	/* apply lapack function according to symmetry */
+	if(symmetric){	
+		C2F(dsyev)( "V", "U", &rows, inCopy, &rows, outReal, pdblWork, &iWorkSize, &INFO );
+	
+		/* Computation of eigenvectors */
+		for (i=0;i<rows*rows;i++) 	eigenvectors[i] = inCopy[i];
+	}
+	else {	
+		pdblRightvectors=(double*)malloc((unsigned int)(rows*rows) * sizeof(double));
+		outImag = (double*)malloc((unsigned int)rows * sizeof(double));
+		C2F(dgeev)( "N", "V", &rows, inCopy, &rows, outReal, outImag,
+        			pdblLeftvectors, &rows, pdblRightvectors, &rows, pdblWork, &iWorkSize, &INFO );  
+	
+		/* Computation of eigenvectors */        			
+        	j=0;
+		while (j<rows)
+		{
+			if (outImag[j]==0)
+			{	
+				for(i = 0 ; i < rows ; i++)
+				{
+					ij = i + j * rows;
+					eigenvectors[ij] = pdblRightvectors[ij];
+				}
+				j = j + 1;
+			}
+			else
+			{
+				for(i = 0 ; i < rows ; i++)
+				{
+					ij = i + j * rows;
+					ij1 = i + (j + 1) * rows;
+					eigenvectors[ij] = pdblRightvectors[ij];
+					eigenvectors[ij1] = pdblRightvectors[ij];
+				}
+				j = j + 2;
+			}
+		}
+	}
+	
+	/* Computation of eigenvalues */
+	dzerosa(eigenvalues,1,rows*rows);
+	for (i=0;i<rows;i++) eigenvalues[i+i*rows]=outReal[i];
+	
+
+	
+
+	free(inCopy);
+	free(outReal);
+	free(outImag);
+	free(pdblLeftvectors);
+	free(pdblRightvectors);
+	free(pdblWork);
+
+}
+