Thread: Segmentation Fault (core dumped).. this is what it said when i compiled

okay so i think i need to finish this and im done and like i said tis isnt my entire program
but can i get help with figuring whats wrong
im sure the error is here somewhere too

Code:

void prob2(void)
{
 FILE *input_1;
 input_1=fopen("inputf.dat", "r");
 if(input_1==NULL) exit(1);
 
 int m, q, i, j, n, k;
 char line[64];
 double **A, *x;
 A=(double **)calloc(4,sizeof(double *));
 for(i=0;i<4;i++)
 	A[i]=(double *)calloc(4 ,sizeof(double));
 x=(double *)malloc(4*sizeof(double));
 
 k=0;
 while(fgets(line,64,input_1) != NULL)
 {
  if(k==4)
    sscanf(line, "%lf %lf %lf %lf", &x[0],&x[1],&x[2],&x[3]);
  else
   {
   sscanf(line, "%lf %lf %lf %lf", &A[m][0],&A[m][1],&A[m][2],&A[m][3]);
   }
  k++;
 
 }
 
printf("Matrix A is:");
printf("\n\n");
for(q=0;q<4;q++)
	printf("%6.3f ",A[0][q]);
printf("\n");

for(q=0;q<4;q++)
	printf("%6.3f ",A[1][q]);
printf("\n");

for(q=0;q<4;q++)
	printf("%6.3f ",A[2][q]);
printf("\n");

for(q=0;q<4;q++)
	printf("%6.3f ",A[3][q]);
printf("\n\n");

printf("Vector x is:");
printf("\n\n");
printf(" x[] =  ");
for(j=0;j<4;j++)
	printf("%6.3f  ",x[j]);
printf("\n\n");


n=4;
double **A_s;
A_s=(double **)calloc(4,sizeof(double *));
for(i=0;i<4;i++)
	A_s[i]=(double *)calloc(4 ,sizeof(double));
A_s = smatrix (A,x,n);

printf("Matrix A_s is:\n\n ");
for(q=0;q<4;q++)
printf("%6.3f ",A_s[0][q]);
printf("\n");

for(q=0;q<4;q++)
printf("%6.3f ",A_s[1][q]);
printf("\n");

for(q=0;q<4;q++)
printf("%6.3f ",A_s[2][q]);
printf("\n");

for(q=0;q<4;q++)
printf("%6.3f ",A_s[3][q]);
printf("\n\n");

printf("Vector y is:");
printf("\n\n");
printf(" y[] =  ");

double *y;
y =(double *)malloc(n*sizeof(double));
y = dotp2(A_s,x,n);
double norm;
norm = norm2(x,n);
for (i=0;i<n;i++)
	y[i]=y[i]/norm;
for(q=0;q<4;q++)
	printf("%6.3f  ",y[q]);
printf("\n\n");
free(A);
free(A_s);
free(x);
free(y);
}