+// converts a matrix4x4 to a double[16] array in the OpenGL orientation
+void Matrix4x4_ToArrayDoubleGL(const matrix4x4_t *in, double out[16]);
+// creates a matrix4x4 from a double[16] array in the OpenGL orientation
+void Matrix4x4_FromArrayDoubleGL(matrix4x4_t *out, const double in[16]);
+// converts a matrix4x4 to a double[16] array in the Direct3D orientation
+void Matrix4x4_ToArrayDoubleD3D(const matrix4x4_t *in, double out[16]);
+// creates a matrix4x4 from a double[16] array in the Direct3D orientation
+void Matrix4x4_FromArrayDoubleD3D(matrix4x4_t *out, const double in[16]);
+
+// converts a matrix4x4 to a float[12] array in the OpenGL orientation
+void Matrix4x4_ToArray12FloatGL(const matrix4x4_t *in, float out[12]);
+// creates a matrix4x4 from a float[12] array in the OpenGL orientation
+void Matrix4x4_FromArray12FloatGL(matrix4x4_t *out, const float in[12]);
+// converts a matrix4x4 to a float[12] array in the Direct3D orientation
+void Matrix4x4_ToArray12FloatD3D(const matrix4x4_t *in, float out[12]);
+// creates a matrix4x4 from a float[12] array in the Direct3D orientation
+void Matrix4x4_FromArray12FloatD3D(matrix4x4_t *out, const float in[12]);
+
+// creates a matrix4x4 from an origin and quaternion (used mostly with skeletal model formats such as PSK)
+void Matrix4x4_FromOriginQuat(matrix4x4_t *m, double ox, double oy, double oz, double x, double y, double z, double w);
+// creates a matrix4x4 from an origin and canonical unit-length quaternion (used mostly with skeletal model formats such as MD5)
+void Matrix4x4_FromDoom3Joint(matrix4x4_t *m, double ox, double oy, double oz, double x, double y, double z);
+