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/*******************************************************************/
/*** FILE : ReduceMatrix.c ***/
/*** AUTHOR: David P Jacobs ***/
/*** PROGRAMMER: Sekhar Muddana ***/
/*** DATE WRITTEN: May 1990. ***/
/*** MODIFIED: David Lee (Aug 1992). ***/
/*** - Added code to gather statistics. ***/
/*** PUBLIC ROUTINES: ***/
/*** int ReduceMatrix() ***/
/*** PRIVATE ROUTINES: ***/
/*** MODULE DESCRIPTION: ***/
/*******************************************************************/
#include <stdio.h>
#include "Build_defs.h"
#include "CreateMatrix.h"
#define assert_not_null(p) if (p == NULL) return(0)
/*********************
These are for density measurement on last matrix.
*********************/
extern short int gather_density_flag;
extern long unsigned int num_elements;
extern long unsigned int max_num_elements;
static Matrix TheMatrix;
static int Num_rows;
static int Num_cols;
int ReduceTheMatrix(Mptr,Rows,Cols,Rank)
Matrix Mptr;
int Rows;
int Cols;
int *Rank;
{
int i,j;
int nextstairrow = 0; /* next row with stair step 1 */
Scalar S_zero();
TheMatrix = Mptr;
Num_rows = Rows;
Num_cols = Cols;
if ((Rows == 0) || (Cols == 0))
return(OK);
assert_not_null(Mptr);
for (i=0;i<Num_cols;i++) {
for (j=nextstairrow;j<Num_rows;j++) {
if (TheMatrix[j*Num_cols + i] != S_zero())
break;
}
if (j<Num_rows) {
Interchange(nextstairrow,j);
Knockout(nextstairrow,i);
nextstairrow++;
}
}
*Rank = nextstairrow;
return(OK);
}
Interchange(Row1,Row2)
int Row1,Row2;
{
int j;
int row1_start,row2_start;
Scalar temp;
row1_start = Row1 * Num_cols;
row2_start = Row2 * Num_cols;
for (j=0;j<Num_cols;j++) {
temp = TheMatrix[row1_start + j];
TheMatrix[row1_start + j] = TheMatrix[row2_start + j];
TheMatrix[row2_start + j] = temp;
}
}
Knockout(Row,Col)
int Row;
int Col;
{
Scalar S_one();
Scalar S_inv();
Scalar S_minus();
int j;
Scalar x;
Scalar one = S_one();
if ((x = TheMatrix[Row*Num_cols + Col]) != one)
MultRow(Row,S_inv(x));
for (j=0;j<Row;j++)
AddRow(S_minus(TheMatrix[j*Num_cols + Col]),Row,j);
for (j=Row+1;j<Num_rows;j++)
AddRow(S_minus(TheMatrix[j*Num_cols + Col]),Row,j);
}
MultRow(Row,Factor)
int Row;
Scalar Factor;
{
Scalar S_mul();
int j;
int row_start = Row * Num_cols;
for (j=0;j<Num_cols;j++)
{
TheMatrix[row_start + j] = S_mul(TheMatrix[row_start + j],Factor);
}
}
AddRow(Factor,Row1,Row2)
Scalar Factor;
int Row1,Row2;
{
Scalar S_zero();
Scalar S_add();
Scalar S_mul();
Scalar before;
Scalar after;
int j;
int row1_start,row2_start;
if (Factor == S_zero())
return;
row1_start = Row1 * Num_cols;
row2_start = Row2 * Num_cols;
for (j=0;j<Num_cols;j++)
{
before = TheMatrix[row2_start+j];
TheMatrix[row2_start + j] = S_add(TheMatrix[row2_start + j],
S_mul(Factor,TheMatrix[row1_start + j]));
if (gather_density_flag)
{
after = TheMatrix[row2_start+j];
if ((before==S_zero()) && (after != S_zero()))
{
num_elements++;
if (num_elements > max_num_elements)
{
max_num_elements=num_elements;
}
}
if ((before!=S_zero()) && (after == S_zero()))
num_elements--;
}
}
}
/*
int GetRank()
{
Scalar S_zero();
int i,j;
int rank = 0;
for (i=0;i<Num_rows;i++) {
for (j=0;j<Num_cols;j++) {
if (TheMatrix[i*Num_cols + j] != S_zero()) {
rank++;
break;
}
}
}
return(rank);
}
*/
PrintTheRMatrix()
{
int i,j,k=0;
printf("The Reduced Matrix is : \n");
for (i=0;i<Num_rows;i++) {
for (j=0;j<Num_cols;j++) {
printf(" %3d",TheMatrix[i*Num_cols + j]);
k = (k + 1)%25;
if (k == 0)
printf("\n");
}
k = 0;
printf("\n");
}
printf("\n");
}
/*
main()
{
void S_init();
S_init();
CreateRandomMatrix();
ReduceTheMatrix();
PrintTheRMatrix();
printf("Num_rows = %d Rank = %d\n",Num_rows,GetRank());
}
CreateRandomMatrix()
{
char *Mymalloc();
int i,j,k;
int Num_cells;
Num_cols = Num_rows = rand() % 10 + 10;
Num_cells = Num_rows * Num_cols;
TheMatrix = (Scalar *) (Mymalloc(Num_cells * sizeof(Scalar)));
assert_not_null(TheMatrix);
for (i=0;i<Num_rows;i++)
for (j=0;j<Num_rows;j++)
TheMatrix[i*Num_rows + j] = 0;
for (i=0;i<(Num_rows-4);i++)
TheMatrix[i*Num_rows +i] = 1;
PrintTheRMatrix();
printf("Before reduction: Rank = %d\n",GetRank());
for (i=0;i<25;i++) {
Interchange(rand()%Num_rows,rand()%Num_rows);
MultRow(rand()%Num_rows,rand()%25);
AddRow(rand()%25,rand()%Num_rows,rand()%Num_rows);
}
return(1);
}
*/
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