Matrix Multiplication - C Program

Submitted by davidwachira on Sunday, August 4, 2013 - 20:07.
Language
C/C++
A program that can be used to multiply two matrices. It uses the following algorithm: Step 1: Make sure that the the number of columns in the 1st one equals the number of rows in the 2nd one. (The pre-requisite to be able to multiply) Step 2: Multiply the elements of each row of the first matrix by the elements of each column in the second matrix. Step 3: Add the products.
  1. #include <stdio.h>
  2.  
  3.  
  4.  
  5.    //Variable declaration and initialization
  6.   int first_matrix_rows, first_matrix_columns;
  7.   int second_matrix_rows, second_matrix_columns;
  8.   int matrix_rows_counter, matrix_columns_counter;
  9.   int matrix_calculation_counter;
  10.   int matrix_calculation_holder = 0;
  11.   int first_matrix_array[20][20];
  12.   int second_matrix_array[20][20];
  13.   int product_matrix_array[20][20];
  14.  
  15. int main(void)//Main method
  16. {
  17.  
  18.   //Prompt user to enter the rows of the first matrix and its capture and storage
  19.   printf("Please enter the number of rows of the first matrix\n");
  20.   scanf("%d", &first_matrix_rows);
  21.  
  22.   //Prompt user to enter the columns of the first matrix and its capture and storage
  23.   printf("Please enter the number of columns of the first matrix\n");
  24.   scanf("%d", &first_matrix_columns);
  25.  
  26.   //Prompt user to enter the elements of the first matrix
  27.   printf("Enter the elements of the first matrix\n");
  28.  
  29.   //Capture and storage of the elements of the first matrix through and array called first_matrix_array[][]
  30.   for (matrix_rows_counter = 0 ; matrix_rows_counter < first_matrix_rows ; matrix_rows_counter++ )
  31.     {  for ( matrix_columns_counter = 0 ; matrix_columns_counter < first_matrix_columns ; matrix_columns_counter++ )
  32.          {
  33.           scanf("%d", &first_matrix_array[matrix_rows_counter][matrix_columns_counter]);
  34.          }
  35.     }
  36.  
  37.   //Prompt user to enter the rows of the second matrix and its capture and storage
  38.   printf("Enter the number of rows of second matrix\n");
  39.   scanf("%d", &second_matrix_rows);
  40.  
  41.   //Prompt user to enter the columns of the second matrix and its capture and storage
  42.   printf("Enter the number of columns of second matrix\n");
  43.   scanf("%d", &second_matrix_rows, &second_matrix_columns);
  44.  
  45.   //Test the prerequisite for matrix multiplication. Make sure that the the number of columns in the 1st one equals the number of rows in the 2nd one.
  46.   if ( first_matrix_columns != second_matrix_rows )
  47.     printf("Matrix 1 and 2 cannot be multiplied together because the number of columns in 1 does not equal the number of rows in 2. In this case, the multiplication of these two matrices is not defined. \n");
  48.   else
  49.   {
  50.     //Prompt user to enter the elements of the second matrix
  51.     printf("Enter the elements of second matrix\n");
  52.  
  53.     //Capture and storage of the elements of the second matrix through and array called first_matrix_array[][]
  54.     for ( matrix_rows_counter = 0 ; matrix_rows_counter < second_matrix_rows ; matrix_rows_counter++ )
  55.       for ( matrix_columns_counter = 0 ; matrix_columns_counter < second_matrix_columns ; matrix_columns_counter++ )
  56.         scanf("%d", &second_matrix_array[matrix_rows_counter][matrix_columns_counter]);
  57.  
  58.     //Multiply the elements of the matrix, row by column, one after the other and storage into a third matrix known as product_matrix_array[][]
  59.     for ( matrix_rows_counter = 0 ; matrix_rows_counter < first_matrix_rows ; matrix_rows_counter++ )
  60.     {
  61.       for ( matrix_columns_counter = 0 ; matrix_columns_counter < second_matrix_columns ; matrix_columns_counter++ )
  62.       {
  63.         for ( matrix_calculation_counter = 0 ; matrix_calculation_counter< second_matrix_rows ; matrix_calculation_counter++ )
  64.         {
  65.           matrix_calculation_holder = matrix_calculation_holder + first_matrix_array[matrix_rows_counter][matrix_calculation_counter]*second_matrix_array[matrix_calculation_counter][matrix_columns_counter];
  66.         }
  67.  
  68.         product_matrix_array[matrix_rows_counter][matrix_columns_counter] = matrix_calculation_holder;
  69.         matrix_calculation_holder = 0;
  70.       }
  71.     }
  72.  
  73.     //A simple output segment preceeding the product of the multiplication
  74.     printf("The product of the matrix multiplication is:\n");
  75.  
  76.     //Display of the elements of the third array named product_matrix_array[][]
  77.     for ( matrix_rows_counter = 0 ; matrix_rows_counter < first_matrix_rows ; matrix_rows_counter++ )
  78.     {
  79.       for ( matrix_columns_counter = 0 ; matrix_columns_counter < second_matrix_columns ; matrix_columns_counter++ )
  80.         printf("%d\t", product_matrix_array[matrix_rows_counter][matrix_columns_counter]);
  81.  
  82.       printf("\n");
  83.     }
  84.   }
  85.  
  86.   return 0;
  87. }
  88.  
  89.  
  90.  
  91. <c>

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Tags
c program to multiply matrices
matrix multiplication in c

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