void BPMatMul( float A[2][3], float B[2][3], float C[2][3] );
// apply a rotation (degrees)
void BPMatRotate( float A[2][3], float theta );
void BPMatMul( float A[2][3], float B[2][3], float C[2][3] );
// apply a rotation (degrees)
void BPMatRotate( float A[2][3], float theta );