1 files changed, 123 insertions, 0 deletions
diff --git a/mons_math/src/mat2.c b/mons_math/src/mat2.c
new file mode 100644
index 0000000..026b165
--- /dev/null
+++ b/mons_math/src/mat2.c
@@ -0,0 +1,123 @@
+#include "mons_math/mat2.h"
+
+const mons_mat2 MONS_MAT2_ZERO = {
+    {0, 0},
+    {0, 0},
+};
+
+const mons_mat2 MONS_MAT2_IDENTITY = {
+    {1, 0},
+    {0, 1},
+};
+
+mons_mat2 mons_mat2_add(mons_mat2 a, mons_mat2 b) {
+    mons_mat2 result = {
+        mons_vec2_add(a.m1, b.m1),
+        mons_vec2_add(a.m2, b.m2),
+    };
+    return result;
+}
+
+void mons_mat2_add_inplace(mons_mat2 *a, mons_mat2 b) {
+    mons_vec2_add_inplace(&a->m1, b.m1);
+    mons_vec2_add_inplace(&a->m2, b.m2);
+}
+
+mons_mat2 mons_mat2_mul_f(mons_mat2 a, float b) {
+    mons_mat2 result = {
+        mons_vec2_mul_f(a.m1, b),
+        mons_vec2_mul_f(a.m2, b),
+    };
+    return result;
+}
+
+mons_mat2 mons_mat2_mul_i(mons_mat2 a, int b) {
+    mons_mat2 result = {
+        mons_vec2_mul_i(a.m1, b),
+        mons_vec2_mul_i(a.m2, b),
+    };
+    return result;
+}
+
+mons_mat2 mons_mat2_mul(mons_mat2 a, mons_mat2 b) {
+    mons_vec2 b_n1 = mons_mat2_n1(b);
+    mons_vec2 b_n2 = mons_mat2_n2(b);
+
+    mons_mat2 result = {
+        {
+            mons_vec2_dot(a.m1, b_n1),
+            mons_vec2_dot(a.m1, b_n2),
+        },
+        {
+            mons_vec2_dot(a.m2, b_n1),
+            mons_vec2_dot(a.m2, b_n2),
+        },
+    };
+    return result;
+}
+
+void mons_mat2_mul_f_inplace(mons_mat2 *a, float b) {
+    mons_vec2_mul_f_inplace(&a->m1, b);
+    mons_vec2_mul_f_inplace(&a->m2, b);
+}
+
+void mons_mat2_mul_i_inplace(mons_mat2 *a, int b) {
+    mons_vec2_mul_i_inplace(&a->m1, b);
+    mons_vec2_mul_i_inplace(&a->m2, b);
+}
+
+mons_mat2 mons_mat2_transpose(mons_mat2 a) {
+    mons_mat2 result = {
+        mons_mat2_n1(a),
+        mons_mat2_n2(a),
+    };
+    return result;
+}
+
+void mons_mat2_transpose_inplace(mons_mat2 *a) { *a = mons_mat2_transpose(*a); }
+
+mons_vec2 mons_mat2_n1(mons_mat2 a) {
+    mons_vec2 result = {
+        a.m1.x,
+        a.m2.x,
+    };
+    return result;
+}
+
+mons_vec2 mons_mat2_n2(mons_mat2 a) {
+    mons_vec2 result = {
+        a.m1.y,
+        a.m2.y,
+    };
+    return result;
+}
+
+float mons_mat2_determinant(mons_mat2 a) {
+    // ad - bc
+    return (a.m1.x * a.m2.y) - (a.m1.y * a.m2.x);
+}
+
+mons_mat2 mons_mat2_adjoint(mons_mat2 a) {
+    /*
+     * d -b
+     * -c a
+     */
+    mons_mat2 result = {{
+                            a.m2.y,
+                            -a.m1.y,
+                        },
+                        {
+                            -a.m2.x,
+                            a.m1.x,
+                        }};
+    return result;
+}
+
+mons_mat2 mons_mat2_inverse(mons_mat2 a) {
+    return mons_mat2_mul_f(mons_mat2_adjoint(a),
+                           1.0 / mons_mat2_determinant(a));
+}
+
+int mons_mat2_equal(mons_mat2 a, mons_mat2 b) {
+    return mons_vec2_equal(a.m1, b.m1) && mons_vec2_equal(a.m2, b.m2);
+}