def tem(fEM, off, freq, time, signal, ft, ftarg, conv=True):
    r"""Return the time-domain response of the frequency-domain response fEM.

    This function is called from one of the above modelling routines. No
    input-check is carried out here. See the main description of :mod:`model`
    for information regarding input and output parameters.

    This function can be directly used if you are sure the provided input is in
    the correct format. This is useful for inversion routines and similar, as
    it can speed-up the calculation by omitting input-checks.

    """
    # 1. Scale frequencies if switch-on/off response
    # Step function for causal times is like a unit fct, therefore an impulse
    # in frequency domain
    if signal in [-1, 1]:
        # Divide by signal/(2j*pi*f) to obtain step response
        fact = signal/(2j*np.pi*freq)
    else:
        fact = 1

    # 2. f->t transform
    tEM = np.zeros((time.size, off.size))
    for i in range(off.size):
        out = getattr(transform, ft)(fEM[:, i]*fact, time, freq, ftarg)
        tEM[:, i] += out[0]
        conv *= out[1]

    return tEM*2/np.pi, conv
r"""Return the time-domain response of the frequency-domain response fEM.

    This function is called from one of the above modelling routines. No
    input-check is carried out here. See the main description of :mod:`model`
    for information regarding input and output parameters.

    This function can be directly used if you are sure the provided input is in
    the correct format. This is useful for inversion routines and similar, as
    it can speed-up the calculation by omitting input-checks.