def reactor_interpolate(interp_time, state1, state2):
    """Linearly interpolate the reactor states to the given input time.

    :param interp_time:
        Time at which the interpolated values should be calculated
    :param state1:
        Array of the state information at the previous time step.
    :param state2:
        Array of the state information at the current time step.
    """
    interp_state = state1 + ((state2 - state1)*(interp_time - state1[0]) /
                             (state2[0] - state1[0]))
    return interp_state