Question

write a C program that will ask the user to input an integer “n” at the console. Your program will generate two n x n matrices of random ints between 0 and 1023 (inclusive), then multiply, add, and subtract them together. The matrices are to be represented as 2-dimensional arrays. Your program should display the result of each matrix operation (multiplication, subtraction and addition). Write a report explaining for which value of n your program performance slows down.

Answer 1

#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <malloc.h>
#include <windows.h>
void printmatrix(int**, int);

int main(){
srand((unsigned)time(NULL));
int n,i,j;
printf("Input n: ");
scanf("%d",&n);
int** first = (int**)malloc(sizeof(int*)*n);
int** second = (int**)malloc(sizeof(int*)*n);
int** result = (int**)malloc(sizeof(int*)*n);
for(i = 0 ; i < n; i++){
first[i] = (int*)malloc(sizeof(int)*n);
second[i] = (int*)malloc(sizeof(int)*n);
result[i] = (int*)malloc(sizeof(int)*n);
}
for(i = 0 ; i < n ; i++)
for(j = 0 ; j < n ; j++){
first[i][j] = rand()%1024;
second[i][j] = rand()%1024;
}
printf("First massive\n");
printmatrix(first,n);
printf("Second massive\n");
printmatrix(second,n);
//+
for(i = 0; i < n; i++)
for(j = 0; j < n; j++)
result[i][j] = first[i][j] + second[i][j];
printf("Sum of first and second\n");
printmatrix(result,n);
//-
for(i = 0; i < n; i++)
for(j = 0; j < n; j++)
result[i][j] = first[i][j] - second[i][j];
printf("Subtract of first and second\n");
printmatrix(result,n);
//*
for(i = 0; i < n; i++)
for(j = 0; j < n; j++)
result[i][j] = first[i][j] * second[i][j];
printf("Multiply of first and second\n");
printmatrix(result,n);
for(i = 0 ; i < n; i++){
free(first[i]);
free(second[i]);
free(result[i]);
}
free (first);
free (second);
free (result);
return 0;
}

void printmatrix(int** mass, int size){
int i, j;
for(i = 0 ; i < size; i++){
for(j = 0 ; j < size; j++)
printf("%8d",mass[i][j]);
printf("\n");
}
printf("\n\n");
}