1 #include <stdio.h> 2 #include <stdlib.h> 3 4 typedef enum { 5 OK, 6 ERROR_MEMORY_ALLOC, 7 ERROR_NULL_POINTER 8 } status_t; 9 10 status_t identity_matrix(size_t dim, double ***m); 11 12 int main (void) 13 { 14 double **m; 15 size_t len = 5; 16 if(!identity_matrix(len, &m)); 17 18 for(size_t i = 0; i < len; i++) { 19 for(size_t j = 0; j < len; j++) 20 printf("%.0f ", m[i][j]); 21 22 putchar('\n'); 23 } 24 25 return 0; 26 } 27 28 status_t identity_matrix(size_t dim, double ***m) 29 { 30 if(!m) return ERROR_NULL_POINTER; 31 32 /* Allocates memory for a squared matrix of dimension dim */ 33 if(!(*m = (double **)malloc(sizeof(double) * (dim * dim)))) return ERROR_MEMORY_ALLOC; 34 35 /* Gets memory for every element of the matrix, if an error occurs, frees every previous allocated element and returns ERROR_NULL_POINTER, if no errors are enconuntered and both indexes are equal stores a 1 otherwise leaves it at zero */ 36 for(size_t i = 0; i < dim; i++) { 37 if(!((*m)[i] = (double *)calloc(sizeof(double), dim))) { 38 for(size_t k = i; k--;) free((*m)[k]); 39 return ERROR_MEMORY_ALLOC; 40 } 41 for(size_t j = 0; j < dim; j++) { 42 if(i == j) (*m)[i][j] = 1; 43 else (*m)[i][j] = 0; 44 } 45 } 46 47 return OK; 48 }
