[math] Matrix get value at row, column index

src/matrix.c

@@ -1,6 +1,5 @@
 #include "matrix.h"
 
-
 matrix_t *matrix_new(size_t m, size_t n) {
     matrix_t *matrix = malloc(sizeof(matrix_t));
 
@@ -50,6 +49,11 @@ inline void matrix_set_scalar(matrix_t *self, size_t row_index, size_t col_index
     values[offset] = value;
 }
 
+inline double matrix_get(matrix_t *self, size_t row_index, size_t col_index) {
+    size_t index = row_index * self->n + col_index;
+    return self->values->a[index];
+}
+
 inline matrix_t *matrix_new_value(size_t m, size_t n, double value) {
     matrix_t *matrix = matrix_new(m, n);
     matrix_set(matrix, value);

src/matrix.h

@@ -25,6 +25,8 @@ void matrix_set(matrix_t *self, double value);
 void matrix_set_row(matrix_t *self, size_t index, double *row);
 void matrix_set_scalar(matrix_t *self, size_t row_index, size_t col_index, double value);
 
+double matrix_get(matrix_t *self, size_t row_index, size_t col_index);
+
 void matrix_scale(matrix_t *self, double value);
 void matrix_dot_vector(matrix_t *self, double *vec, double *result);
 int matrix_dot_matrix(matrix_t *m1, matrix_t *m2, matrix_t *result);