/* 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: Siddhesh Wani
 Organization: FOSSEE, IIT Bombay
 Email: toolbox@scilab.in
*/

#include <stdlib.h>
#ifndef WITHOUT_LAPACK
#include "lapack.h"
#endif
#include "determ.h"
#include "lapack.h"

int8 i8determa(int8 * in, int size){
#ifndef WITHOUT_LAPACK
	int i=0, info=0;
	int8 out=0;
	int8 *inCopy=NULL;
	int* tmp=NULL;
	
	/*Calculation of the determinant*/
	switch (size){
		case 2 : out = in[0]*in[3]-in[1]*in[2];
			 break;
		case 3 : /*regle de Sarrus*/
			 out = in[0]*in[4]*in[8]+in[1]*in[5]*in[6]+in[2]*in[3]*in[7]
			      -in[0]*in[5]*in[7]-in[1]*in[3]*in[8]-in[2]*in[4]*in[6];
			 break;
		default : 
		
			  /*Copy the input matrix*/
			  inCopy=(int8*)malloc((unsigned int)(size*size)*sizeof(int8));
			  for (i=0;i<size*size;i++) inCopy[i]=in[i];

			  tmp=(int*)malloc((unsigned int)size*sizeof(int));			  
			  dgetrf_(&size, &size, inCopy, &size, tmp, &info);
			  out=1;
			  for (i=0;i<size;i++){
			  	if (tmp[i]!=i+1) out=-out;
			  	out=inCopy[i*(size+1)]*out;
			  }
			  free(tmp);
			  free(inCopy);
			  break;
	}
	
#else
	int i=0, j=0, k=0;
	int8 out=0, pivot=0;
	int8 *inCopy=NULL;
	
	/*Calculation of the determinant*/
	switch (size){
		case 2 : out = in[0]*in[3]-in[1]*in[2];
			 break;
		case 3 : /*regle de Sarrus*/
			 out = in[0]*in[4]*in[8]+in[1]*in[5]*in[6]+in[2]*in[3]*in[7]
			      -in[0]*in[5]*in[7]-in[1]*in[3]*in[8]-in[2]*in[4]*in[6];
			 break;
		default : 
				
				  /*Copy the input matrix*/
			  inCopy=malloc((unsigned int)(size*size)*sizeof(int8));
			  for (i=0;i<size*size;i++) inCopy[i]=in[i];
			  
    			  for (i=0;i<size;i++){
				for (j=i+1;j<size;j++){
					pivot = inCopy[i*size+j]/inCopy[i*size+i];
					for (k=0;k<size-i;k++){
						inCopy[i*size+j+k*size]-=pivot*inCopy[i*size+i+k*size];
					}
				}
			  }
			  out=1;
			  for (i=0;i<size;i++){
			  	out *= inCopy[i*size+i];
			  }
			  free(inCopy);
			  break;
		
	}
#endif


	return out;	
}