def subtract_mult(self, mat2, alpha = 1.):
    """
    Subtract a multiple of mat2 from the matrix.
    """

    err_code = _eigenmat.add_mult(self.p_mat, mat2.p_mat, ct.c_float(-1. * alpha))
    if err_code:
      raise generate_exception(err_code)

    return self

    Subtract a multiple of mat2 from the matrix.
    
eigenmat/eigenmat.py