Stuck on allocating a matrix from a file and reusing that to compute another

[craziileeboi]

Hi

I have been pulling my hair out trying to figure this out. Please help!!!

Here is my project description:

By using a pointer to pointers **A and **B and the function calloc()
allocate the memory for the 4x4 matrices A[][] and B[][].
By using the pointers *a and *b and the function malloc()
allocate the memory for the 4-dimensional vectors a[] and b[].
Read the components of a and A from the given input file matrix.dat
(which is in the public/final directory; you need to copy it into your directory).
The first line of the input file contains the components of a. The rows of
matrix A are the last four lines of the input file. Print the components
of a[] and A[][]. By calling the function pmatrix(A,B,a,b,n), n=4,
which you will construct, determine the components of the matrix B=1.5*A*A, and the
vector b=(A*a)+0.5*a. Print the components of the matrix B and the vector b in the main.
Free dinamically allocated memory.
.................................................. ..............................
Output should look like:


Vector a is:
a[] = -1.200 1.200 -2.000 -0.500
Matrix A is:
2.700 1.500 3.200 2.400
-3.200 0.700 -2.600 4.300
1.400 0.600 2.100 -1.800
1.500 1.700 -2.600 -0.700
Matrix B is:
..... ...... ...... ......
..... ...... ...... ......
..... ...... ...... ......
..... ...... ...... ......
Vector b is:
b[] = ..... ..... ..... .....

void prob2(void)
{
FILE *matrix;
int k, z, c;
double **A, **B, *a, *b;
 
 
matrix=fopen("matrix.dat", "r");
if(matrix == NULL){
        printf("Error in file opening for *matrix.\n");
        exit(1);
        }
 
 
A= (double **)calloc((size_t)4, sizeof(double *));
B= (double **)calloc((size_t)4, sizeof(double *));
a= (double *)malloc((size_t) 4 * sizeof(double));
b= (double *)malloc((size_t) 4 * sizeof(double));
 
for(z=0; z<4; z++){
        A[z] = (double *)calloc((size_t)4, sizeof(double *));
}
for(z=0; z<4; z++)
        for(c=0; c<4;c++) A[z][c] = (double)z * (double)c;
printf("\n");
printf("Matrix A is:\n\n");
 
        for(row=0; row<4; row++){
                for(col=0; col<4; col++){
                fscanf(matrix, "%lf", A+col);
                }
        for(col=0; col<4; col++)
                printf(" %7.3f", A[col]);
        printf("\n");
        }
 
printf("\nVector a is:\n\n");
        for(row=0; row<5; row++){
                for(col=0; col<4; col++){
                fscanf(matrix, "%lf", A+col);
                }
        }
printf("a[] = ");
        for(col=0; col<4; col++)
                printf(" %7.3f", A[col]);
        printf("\n");
 
printf("\n");
printf("Matrix B is: \n\n");
 
}

[craziileeboi]

I can get the program to scan the file and print out the correct information but from there to the next part of computing B i am lost and cant seem to find how to multiply matrices etc

[craziileeboi]

My current problem is the fact taht i keep getting Segmentation Faults and its right when i try to execute pmatrix in void prob2().

[craziileeboi]

NEWLY UPDATED PROGRAM

void prob2(void)
{
 
 
FILE *matrix;
int k, z, c;
double **A,**B, *a, *b, a_norm;
 
 
matrix=fopen("matrix.dat", "r");
if(matrix == NULL){
        printf("Error in file opening for *matrix.\n");
        exit(1);
        }
 
 
A= (double **)calloc((size_t)4, sizeof(double *));
a= (double *)malloc((size_t) 4 * sizeof(double));
b= (double *)malloc((size_t) 4 * sizeof(double));
 
 
 
printf("Matrix A is:\n\n");
 
A = (double **)calloc((size_t)4, sizeof(double *));
        for(row=0; row<4; row++){
                for(col=0; col<4; col++)
                        fscanf(matrix, "%lf", A+col);
                for(col=0; col<4; col++) printf(" %7.2f", A[col]);
        printf("\n");
        }
 
 
 
 
 
 
printf("\nVector a is:\n\n");
        for(row=0; row<5; row++){
                for(col=0; col<4; col++){
                fscanf(matrix, "%lf", A+col);
                }
        }
printf("a[] = ");
        for(col=0; col<4; col++)
                printf(" %7.3f", A[col]);
        printf("\n");
 
printf("\n");
printf("Matrix B is: \n\n");
 
 
 
pmatrix(A, B, a, b, n);
 
 
}
 
void pmatrix(double **A, double **B, double *a, double *b, int n)
{
int k, row, col;
double c[ROWA][COLB], dot_p;
 
 
for(row=0; row<ROWA; row++){
        for(k=0, dot_p=0.; k<COLA; k++){
                dot_p += A[row][k] * A[k][col];}
        c[row][col] = dot_p;
}
        printf("c[%2d][]={", col);
        for(row=0; row<ROWA; row++){
                printf("  %.2f", c[row][col]);
                if((row+1)%5 == 0) printf("\n");
}
 
        printf("}\n");
        return;
}