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#include <stdio.h>
#include <stdlib.h>
/*#include "defs.h"
#include "proto.h"*/
#define MIN(x,y) ((x) > (y) ? (y) : (x))
#include "matrix.h"
/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
R A N K A L G O R I T H M R O U T I N E S
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
int computeRank(int M, int Q, BitField** matrix)
{
int i;
int rank;
int m = MIN(M,Q);
/* FORWARD APPLICATION OF ELEMENTARY ROW OPERATIONS */
for(i = 0; i < m-1; i++) {
if (matrix[i][i].b == 1)
perform_elementary_row_operations(0, i, M, Q, matrix);
else { /* matrix[i][i] = 0 */
if (find_unit_element_and_swap(0, i, M, Q, matrix) == 1)
perform_elementary_row_operations(0, i, M, Q, matrix);
}
}
/* BACKWARD APPLICATION OF ELEMENTARY ROW OPERATIONS */
for(i = m-1; i > 0; i--) {
if (matrix[i][i].b == 1)
perform_elementary_row_operations(1, i, M, Q, matrix);
else { /* matrix[i][i] = 0 */
if (find_unit_element_and_swap(1, i, M, Q, matrix) == 1)
perform_elementary_row_operations(1, i, M, Q, matrix);
}
}
rank = determine_rank(m,M,Q,matrix);
return rank;
}
void perform_elementary_row_operations(int flag, int i, int M, int Q,
BitField** A)
{
int j,k;
switch(flag)
{
case 0: for(j = i+1; j < M; j++)
if (A[j][i].b == 1)
for(k = i; k < Q; k++)
A[j][k].b = (A[j][k].b + A[i][k].b) % 2;
break;
case 1: for(j = i-1; j >= 0; j--)
if (A[j][i].b == 1)
for(k = 0; k < Q; k++)
A[j][k].b = (A[j][k].b + A[i][k].b) % 2;
break;
default: fprintf(stderr,"ERROR IN CALL TO perform_elementary_row_operations\n");
break;
}
return;
}
int find_unit_element_and_swap(int flag, int i, int M, int Q, BitField** A)
{
int index;
int row_op = 0;
switch(flag)
{
case 0: index = i+1;
while ((index < M) && (A[index][i].b == 0))
index++;
if (index < M)
row_op = swap_rows(i,index,Q,A);
break;
case 1:
index = i-1;
while ((index >= 0) && (A[index][i].b == 0))
index--;
if (index >= 0)
row_op = swap_rows(i,index,Q,A);
break;
default: fprintf(stderr,"ERROW IN CALL TO find_unit_element_and_swap\n");
break;
}
return row_op;
}
int swap_rows(int i, int index, int Q, BitField** A)
{
int p;
BitField temp;
for(p = 0; p < Q; p++) {
temp.b = A[i][p].b;
A[i][p].b = A[index][p].b;
A[index][p].b = temp.b;
}
return 1;
}
int determine_rank(int m, int M, int Q, BitField** A)
{
int i, j, rank, allZeroes;
/* DETERMINE RANK, THAT IS, COUNT THE NUMBER OF NONZERO ROWS */
rank = m;
for(i = 0; i < M; i++) {
allZeroes = 1;
for(j=0; j < Q; j++) {
if (A[i][j].b == 1) {
allZeroes = 0;
break;
}
}
if (allZeroes == 1) rank--;
}
return rank;
}
void display_matrix(int M, int Q, BitField** m)
{
int i,j;
for (i = 0; i < M; i++) {
for (j = 0; j < Q; j++)
fprintf(stderr,"%d ", m[i][j].b);
fprintf(stderr,"\n");
}
return;
}
void def_matrix(int M, int Q, BitField** m,int k, int *pt, int *PT, int*DATA, int *ARRAY)
{
int i,j;
for (i = 0; i < M; i++)
for (j = 0; j < Q; j++) {
m[i][j].b = *DATA & 1;
(*PT)++;
if ((*PT) == 32)
{
*PT = 0;
(*pt)++;
*DATA = ARRAY[*pt];
}
else
*DATA = (*DATA) >> 1;
}
return;
}
void delete_matrix(int M, BitField** matrix)
{
int i;
for (i = 0; i < M; i++)
free(matrix[i]);
free(matrix);
}
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