implement matrix_subtract with 1 example in README

main.c

@@ -1,36 +1,8 @@
 #include "matrix/matrix.h"
 #include "fmt/fmt.h"
-#include <time.h>
 
-void fillMatrix(Matrix *mat) {
-    matrix_set(mat, 0, 0, rand() % 10 + 1);
-    matrix_set(mat, 0, 1, rand() % 10 + 1);
-    matrix_set(mat, 1, 0, rand() % 10 + 1);
-    matrix_set(mat, 1, 1, rand() % 10 + 1);
-}
 
 int main() {
-    srand(time(NULL));
-    Matrix* matrix1 = matrix_create(2, 2);
-    Matrix* matrix2 = matrix_create(2, 2);
-
-    if (!matrix1 || !matrix2) {
-        fmt_fprintf(stderr, "Can not create matrix object");
-        exit(-1);
-    }
-
-    fillMatrix(matrix1);
-    fillMatrix(matrix2);
-
-    matrix_print(matrix1);
-    fmt_printf("\n");
-    matrix_print(matrix2);
-
-    Matrix* sum = matrix_add(matrix1, matrix2);
-
-    fmt_printf("\n");
-    matrix_print(sum);
-
-    matrix_deallocate(matrix1);
+
     return 0;
 }

matrix/README.md

@@ -22,4 +22,88 @@ int main() {
     matrix_deallocate(matrix);
     return 0;
 }
+```
+
+## Example 2 : how to add two Matrix with `matrix_add`
+
+```c
+#include "matrix/matrix.h"
+#include "fmt/fmt.h"
+#include <time.h>
+
+void fillMatrix(Matrix *mat) {
+    matrix_set(mat, 0, 0, rand() % 10 + 1);
+    matrix_set(mat, 0, 1, rand() % 10 + 1);
+    matrix_set(mat, 1, 0, rand() % 10 + 1);
+    matrix_set(mat, 1, 1, rand() % 10 + 1);
+}
+
+int main() {
+    srand(time(NULL));
+    Matrix* matrix1 = matrix_create(2, 2);
+    Matrix* matrix2 = matrix_create(2, 2);
+
+    if (!matrix1 || !matrix2) {
+        fmt_fprintf(stderr, "Can not create matrix object");
+        exit(-1);
+    }
+
+    fillMatrix(matrix1);
+    fillMatrix(matrix2);
+
+    matrix_print(matrix1);
+    fmt_printf("\n");
+    matrix_print(matrix2);
+
+    Matrix* sum = matrix_add(matrix1, matrix2);
+
+    fmt_printf("\n");
+    matrix_print(sum);
+
+    matrix_deallocate(sum);
+    matrix_deallocate(matrix1);
+    matrix_deallocate(matrix2);
+
+    return 0;
+}
+```
+
+## Example 3 : subtract two matrix with `matrix_subtract`
+
+```c
+#include "matrix/matrix.h"
+#include "fmt/fmt.h"
+#include <time.h>
+
+void fillMatrix(Matrix *mat) {
+    matrix_set(mat, 0, 0, rand() % 10 + 1);
+    matrix_set(mat, 0, 1, rand() % 10 + 1);
+    matrix_set(mat, 1, 0, rand() % 10 + 1);
+    matrix_set(mat, 1, 1, rand() % 10 + 1);
+}
+
+int main() {
+    srand(time(NULL));
+    Matrix* matrix1 = matrix_create(2, 2);
+    Matrix* matrix2 = matrix_create(2, 2);
+
+    if (!matrix1 || !matrix2) {
+        fmt_fprintf(stderr, "Can not create matrix object");
+        exit(-1);
+    }
+
+    fillMatrix(matrix1);
+    fillMatrix(matrix2);
+
+    Matrix* subtraction = matrix_subtract(matrix1, matrix2);
+
+    fmt_printf("\n");
+    matrix_print(subtraction);
+
+    matrix_deallocate(subtraction);
+    matrix_deallocate(matrix1);
+    matrix_deallocate(matrix2);
+    
+    return 0;
+}
 ```

matrix/matrix.c

@@ -77,6 +77,43 @@ Matrix* matrix_add(const Matrix* matrix1, const Matrix* matrix2) {
 
     return addition;
 }
+
+Matrix* matrix_subtract(const Matrix* matrix1, const Matrix* matrix2) {
+    if (!matrix1) {
+        #ifdef MATRIX_LOGGING_ENABLE  
+            fmt_fprintf(stderr, "Error: matrix1 object is null and invalid in matrix_subtract.\n");
+        #endif 
+        return NULL;
+    }
+    else if (!matrix2) {
+        #ifdef MATRIX_LOGGING_ENABLE  
+            fmt_fprintf(stderr, "Error: matrix2 object is null and invalid in matrix_subtract.\n");
+        #endif 
+        return NULL;
+    }
+    else if ((matrix1->rows != matrix2->rows) || (matrix1->cols != matrix2->cols)) {
+        #ifdef MATRIX_LOGGING_ENABLE  
+            fmt_fprintf(stderr, "Error: The two Matrix are not of the same order in matrix_subtract.\n");
+        #endif 
+        return NULL;
+    }
+
+    Matrix* subtraction = matrix_create(matrix1->rows, matrix1->cols);
+    if (!subtraction) {
+        fmt_fprintf(stderr, "Error: object creation failed for subtraction to matrix in matrix_subtract.\n");
+        return NULL;
+    }
+
+    for (size_t i = 0; i < matrix1->rows; i++) {
+        for (size_t j = 0; j < matrix1->cols; j++) {
+            size_t index = i * matrix1->cols + j;
+            subtraction->data[index] = matrix1->data[index] - matrix2->data[index];
+        }
+    }
+
+    return subtraction;
+}
+
 void matrix_deallocate(Matrix* matrix) {
     if (!matrix) {
         #ifdef MATRIX_LOGGING_ENABLE

matrix/matrix.h

@@ -16,6 +16,7 @@ typedef struct Matrix {
 
 Matrix* matrix_create(size_t rows, size_t cols);
 Matrix* matrix_add(const Matrix* matrix1, const Matrix* matrix2);
+Matrix* matrix_subtract(const Matrix* matrix1, const Matrix* matrix2);
 
 void matrix_deallocate(Matrix* matrix);
 void matrix_print(Matrix* matrix);