Simple convenience function to pad arrays for linear convolution.

    INPUTS:
    in1     (no default):   Input array which is to be padded.

    OUTPUTS:
    out1                    Padded version of the input.

def pad_array(in1):
    """
    Simple convenience function to pad arrays for linear convolution.

    INPUTS:
    in1     (no default):   Input array which is to be padded.

    OUTPUTS:
    out1                    Padded version of the input.
    """

    padded_size = 2*np.array(in1.shape)

    out1 = np.zeros([padded_size[0],padded_size[1]])
    out1[padded_size[0]/4:3*padded_size[0]/4,padded_size[1]/4:3*padded_size[1]/4] = in1

    return out1