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+/* 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
+ */
+
+/* PROJSPEC function in scilab */
+
+/*
+ //[S,P,D,index]=projspec(A)
+ //Spectral characteristics of A at 0
+ //S = reduced resolvent at 0 (S=-Drazin_inverse(A))
+ //P = spectral projection at 0
+ //D = Nilpotent operator at 0
+ //index = index of the 0 eigenvalue
+ //!
+
+*/
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <math.h>
+#include "norm.h"
+#include "eye.h"
+
+#define eps pow(2,-52)
+
+double dprojspeca(double *inp1,int row,int col,double *out1,double *out2,double *out3){
+ double tol = pow(10,-6);
+ int i,j,index;
+ /*norm(A,1)*/
+ double nor;
+ nor = dnorma(inp1,row,col,1);
+
+ /* P=eye(A),D=A,S=0*P;index=1; */
+ if(nor < eps*row*row){
+ memcpy(out2,inp1,row*col*sizeof(double));
+ deyea(out2,row,col);
+ memcpy(out3,inp1,row*col*sizeof(double));
+ for(i=0;i<row;i++){
+ for(j=0;j<row;j++){
+ out1[i*row+j] = 0;
+ }
+ }
+ index = 1;
+ }
+
+ /* rcond(A) */
+ double *rcon;
+ rcon = rcond(inp1,row);
+ if(rcon > tol){
+ dinverma(inp1,out1,row);
+ for(i=0;i<row*col;i++){
+ out2[i]=0;
+ out3[i]=0;
+ }
+ index = 0;
+ return index;
+ }
+ index = 1;
+}