Revert "free dynamically allocated memory and use 1D arrays for simplicity and efficiency"

This reverts commit 56aeff3f07.

numerical_methods/lu_decompose.c

@@ -77,24 +77,6 @@ void display(double **A, int N)
     }
 }
 
-/**
- * Convert a 1D array block into a 2D row-major matrix representation i.e.,
- * elements are ordered row-wise.
- *
- * \param[in] array 1D array to convert
- * \param[in] N_rows number of rows in output matrix
- * \param[in] N_columns number of columns in output matrix
- */
-double **array_to_matrix(const double *array, size_t N_rows, size_t N_cols)
-{
-    double **out;
-    for (size_t row = 0; row < N_rows; row += N_cols)
-    {
-        out[row] = array + (row * N_cols);
-    }
-    return out;
-}
-
 /** Main function */
 int main(int argc, char **argv)
 {
@@ -108,17 +90,15 @@ int main(int argc, char **argv)
     srand(time(NULL)); // random number initializer
 
     /* Create a square matrix with random values */
-    double *a = (double *)calloc(mat_size * mat_size *
-                                 sizeof(double)); // allocate 1D NxN memory
-    double *l = (double *)calloc(mat_size * mat_size *
-                                 sizeof(double)); // allocate 1D NxN memory
-    double *u = (double *)calloc(mat_size * mat_size *
-                                 sizeof(double)); // allocate 1D NxN memory
-    double **A = array_to_matrix(a, mat_size, mat_size);
-    double **L = array_to_matrix(l, mat_size, mat_size); // output
-    double **U = array_to_matrix(u, mat_size, mat_size); // output
+    double **A = (double **)malloc(mat_size * sizeof(double *));
+    double **L = (double **)malloc(mat_size * sizeof(double *)); // output
+    double **U = (double **)malloc(mat_size * sizeof(double *)); // output
     for (int i = 0; i < mat_size; i++)
     {
+        // calloc so that all valeus are '0' by default
+        A[i] = (double *)calloc(mat_size, sizeof(double));
+        L[i] = (double *)calloc(mat_size, sizeof(double));
+        U[i] = (double *)calloc(mat_size, sizeof(double));
         for (int j = 0; j < mat_size; j++)
             /* create random values in the limits [-range2, range-1] */
             A[i][j] = (double)(rand() % range - range2);
@@ -133,9 +113,5 @@ int main(int argc, char **argv)
     printf("\nU = \n");
     display(U, mat_size);
 
-    free(a);
-    free(l);
-    free(u);
-
     return 0;
 }