Question

Write in C code

What to do Write a function with the following signature: float* matrix multiplication(float* left, float* right, int rows, int shared, int columns); The first two arguments are two pointers to the beginning of two matrices with the dimensions (rows,shared) and (shared, columns) correspondingly. The remaining arguments specify these dimensions. The return value will return a pointer to the very beginning of the result matrix. That said, you need to provide the space for the result matrix by dynamically allocating memory within your function. What to submit I ask you to submit the following: Submit your well-structured, well-documented code for the above function. Submit a driver that tests your code as follows: oHard-code the following two matrices into the driver code and then run your function: Left matrix: float left 2)13 (1,2,3),14,5,6) Right matrix: float right[3114 87,8,9,1011,12,13,14),115,16,17,18) Finally, print out the result matrix on the standard output two-dimentionally, i.e. in its natural appearance. Submit a screen shot that shows the printout of your result matrix. Hint Use malloc0 as discussed in class in order to allocate the piece of memory that is going to accommodate your result matrix

Answer 1

# include <stdio.h>
# include <stdlib.h>

float* matrix_multiplication (float*left, float*right,int rows,int shared,int columns) // function to multiply
{
   int i,j,c,d,k;
   float val1,val2,sum=0.00;
   float* res=(float *)malloc(rows*columns*sizeof(float)); // alocatting for the result
   for (i=0;i<rows;i++) // initializing the values with 0 : optional step
   {
       for (j=0;j<columns;j++)
       {
           *(res+i*columns+j)=0;
       }
   }

   for (c = 0; c < rows; c++) { // main process of multiplication begins
      for (d = 0; d < columns; d++) {
        for (k = 0; k < shared; k++) {
          val1=*(left+c*shared+k); //computing the elements
          val2=*(right+k*shared+d);
          sum = sum + val1*val2;
        }
        //printf("%f\n",sum);
        *(res+c*columns+d)= sum; // computing the products
        sum = 0.00; // reinitializing sum
      }
    }

    return res;
}

void main ()
{
   int m,n,p,q,i,j;
   printf("enter the first matrrix dimension\n"); // entering the first mat dimension
   scanf("%d",&m);
   scanf("%d",&n);
   printf("enter the second matrrix dimension\n"); // entering 2nd mat dimension
   scanf("%d",&p);
   scanf("%d",&q);
   float* l=(float *)malloc(m*n*sizeof(float)); // alocating for 1st mat
   float* r=(float *)malloc(p*q*sizeof(float)); // allocating for 2nd mat
   float* result=(float *)malloc(m*q*sizeof(float)); // alolocating for the result

   printf("enter the first matrix\n"); // entering the first matrix
   for (i=0;i<m;i++)
   {
       for (j=0;j<n;j++)
       {
           scanf("%f",(l+i*n+j));
       }
   }
   printf("enter the 2nd matrix\n"); // entering the second matrix
   for (i=0;i<p;i++)
   {
       for (j=0;j<q;j++)
       {
           scanf("%f",(r+i*q+j));
       }
   }
   printf(" the first matrix\n"); // display the first matrix
   for (i=0;i<m;i++)
   {
       for (j=0;j<n;j++)
       {
           printf("%f\t",*(l+i*n+j));
       }
       printf("\n");
   }

   printf(" the second matrix\n"); // display the second matrix
   for (i=0;i<p;i++)
   {
       for (j=0;j<q;j++)
       {
           printf("%f\t",*(r+i*q+j));
       }
       printf("\n");
   }

   result=matrix_multiplication(l,r,m,n,q); // calling the function

   printf(" the result matrix\n"); // display the resultant
   for (i=0;i<m;i++)
   {
       for (j=0;j<q;j++)
       {
           printf("%f\t",*(result+i*q+j));
       }
       printf("\n");
   }
}

output:

enter the first matrrix dimension
2
3
enter the second matrrix dimension
3
4
enter the first matrix
1
2
3
4
5
6
enter the 2nd matrix
7
8
9
10
11
12
13
14
15
16
17
18
the first matrix
1.000000   2.000000   3.000000  
4.000000   5.000000   6.000000  
the second matrix
7.000000   8.000000   9.000000   10.000000  
11.000000   12.000000   13.000000   14.000000  
15.000000   16.000000   17.000000   18.000000  
the result matrix
66.000000   72.000000   78.000000   84.000000  
156.000000   171.000000   186.000000   201.000000