libgimpmath: add gimp_matrix3_equal()

... which compares two matrices.

devel-docs/libgimpmath/libgimpmath3-sections.txt

@@ -38,6 +38,7 @@ gimp_matrix3_is_identity
 gimp_matrix3_is_diagonal
 gimp_matrix3_is_affine
 gimp_matrix3_is_simple
+gimp_matrix3_equal
 gimp_matrix4_identity
 gimp_matrix4_mult
 gimp_matrix4_to_deg

libgimpmath/gimpmath.def

@@ -7,6 +7,7 @@ EXPORTS
 	gimp_matrix2_transform_point
 	gimp_matrix3_affine
 	gimp_matrix3_determinant
+	gimp_matrix3_equal
 	gimp_matrix3_get_type
 	gimp_matrix3_identity
 	gimp_matrix3_invert

libgimpmath/gimpmatrix.c

@@ -891,6 +891,35 @@ gimp_matrix3_is_simple (const GimpMatrix3 *matrix)
   return TRUE;
 }
 
+/**
+ * gimp_matrix3_equal:
+ * @matrix1: The first matrix
+ * @matrix2: The second matrix
+ *
+ * Checks if two matrices are equal.
+ *
+ * Returns: %TRUE the matrices are equal, %FALSE otherwise
+ *
+ * Since: 2.10.16
+ */
+gboolean
+gimp_matrix3_equal (const GimpMatrix3 *matrix1,
+                    const GimpMatrix3 *matrix2)
+{
+  gint i, j;
+
+  for (i = 0; i < 3; i++)
+    {
+      for (j = 0; j < 3; j++)
+        {
+          if (fabs (matrix1->coeff[i][j] - matrix2->coeff[i][j]) > EPSILON)
+            return FALSE;
+        }
+    }
+
+  return TRUE;
+}
+
 /**
  * gimp_matrix4_identity:
  * @matrix: A matrix.

libgimpmath/gimpmatrix.h

@@ -120,6 +120,9 @@ gboolean      gimp_matrix3_is_diagonal     (const GimpMatrix3 *matrix);
 gboolean      gimp_matrix3_is_affine       (const GimpMatrix3 *matrix);
 gboolean      gimp_matrix3_is_simple       (const GimpMatrix3 *matrix);
 
+gboolean      gimp_matrix3_equal           (const GimpMatrix3 *matrix1,
+                                            const GimpMatrix3 *matrix2);
+
 void          gimp_matrix3_transform_point (const GimpMatrix3 *matrix,
                                             gdouble            x,
                                             gdouble            y,