Overflow multiplying matrices
Hello, I seem to have an overflow that is giving me negative numbers instead of positive numbers. I tried using long long int arrays and it is an overflow. The program works for multiplying matrices when they are small numbers and low dimensions but not when I do a 100 x 150 matrix with numbers that are in the ten thousands.
Code:
#include<stdio.h>
#include"global.h"
#include<string.h>
void read_array(FILE *fp, FILE *fp2, long int array1[][NUM_COLUMN], long int array2[][NUM_COLUMN],
int row1, int column1, int row2, int column2);
void print_array(long int array3[][NUM_COLUMN], int row1, int column1, int row2, int column2);
void multiply_array(long int array1[][NUM_COLUMN], long int array2[][NUM_COLUMN], long int array3[][NUM_COLUMN],
int row1, int column1, int row2, int column2);
int main(int argc, char **argv){
char txt[]=".txt";
long int ia[NUM_ROW][NUM_COLUMN];
long int ib[NUM_ROW][NUM_COLUMN];
long int ic[NUM_ROW][NUM_COLUMN];
FILE *fp;
FILE *fp2;
int col1,col2, rowa,rowb;
/* checks for 3 arguments example [lab8 matrix_a.txt matrix_b.txt] */
if(argc!=3){
/*if(strstr(argv[1],txt)!=0){
printf("Usage: %s matrix_(letter).txt\n", argv[1]);
}else{*/
printf("Usage: %s filename2.txt\n", argv[1]);
return -1;
//}
}
/* checks for .txt extension */
if((strstr(argv[1],txt)!=0) && (strstr(argv[2],txt)!=0)){
fp = fopen(argv[1], "r");
fp2 = fopen(argv[2], "r");
if((fp!=0)&&(fp!=0)){
fseek(fp, 0, SEEK_SET);
fseek(fp2, 0, SEEK_SET);
fscanf(fp, "%d %d", &rowa, &col1);
fscanf(fp2, "%d %d", &rowb, &col2);
read_array(fp, fp2, ia, ib, rowa, col1, rowb, col2);
multiply_array(ia, ib, ic, rowa, col1, rowb, col2);
if(col1==rowb)
print_array(ic, rowa, col1,rowb, col2);
fclose(fp);
fclose(fp2);
}else{
printf("%s and %s Not Open\n", argv[1], argv[2]);
exit(-1);
}
}
else
printf("Unrecognized Arguments, files require *.txt extension");
return 0;
}/* main()*/
void read_array(FILE *fp, FILE *fp2, long int array1[][NUM_COLUMN], long int array2[][NUM_COLUMN],
int row1, int column1, int row2, int column2){
int i,j;
//printf("row1 = %d\n", row1);
//printf("row2 = %d\n", row2);
//printf("column1 = %d\n", column1);
//printf("column2 = %d\n", column2);
for(i=0;i<row1;i++){
for(j=0;j<column1;j++)
fscanf(fp,"%d", &array1[i][j]);
fscanf(fp,"\n");
}
for(i=0;i<row2;i++){
for(j=0;j<column2;j++)
fscanf(fp2,"%d", &array2[i][j]);
fscanf(fp2,"\n");
}
}
void print_array(long int array3[][NUM_COLUMN], int row1, int column1, int row2, int column2){
int i,j;
for(i=0;i<row1;i++){
for(j=0;j<column2;j++)
printf("%d ", array3[i][j]);
printf("\n");
}
}
void multiply_array(long int array1[][NUM_COLUMN], long int array2[][NUM_COLUMN], long int array3[][NUM_COLUMN],
int row1, int column1, int row2, int column2){
int i, j, k;
long int sum;
if(column1==row2){
for (i = 0; i < row1; i++) {
for (j = 0; j < column2; j++) {
sum = 0;
for (k = 0; k < row2; k++) {
sum += array1[i][k] * array2[k][j];
}
array3[i][j] = sum;
}
}
}else{
printf("Error in Matrix Multiplication\n");
printf("Cannot multiply when Column1 does not match with Row2 A[%d][%d] B[%d][%d]\n", row1, column1, row2, column2);
}
}
NUM_ROW and NUM_COLUMN defined in global.h as 250 for each.
Could anyone help? Thanks in advance.
