A general handling of sigma equals or close to zero

[yaelbh]

What happens in the different experiments if the ydata's sigma is equal to zero or close to it? Is it what we want to happen? Is it the same for all the experiments?

[yaelbh]

Looks like it's already being taken care of in the curve_fit method:

    # Format non-number sigma values
    if np.all(np.isnan(sigma)):
        sigma = None
    else:
        sigma = np.nan_to_num(sigma)
        if np.count_nonzero(sigma) != len(sigma):
            # Sigma = 0 causes zero division error
            sigma = None