def param_to_str(model, p):
    """Represent value of *p*'th parameter of *model* as a string."""
    parameter = [param for param in model][p]
    # Zeros are not displayed, which declutters the user interface
    if parameter.value == 0.0:
        return ''
    # Represent P9 and P12 (scale parameters) in shorter form
    elif p in [8, 11]:
        return "%.3e" % (parameter.value,)
    else:
        return parameter.value_str