Fractional parameter needs to be able to take non-zero lower bound.

[rutgerfick]

Right now a fractional parameter ranges between [0-1] * some_parameter, but that means that it can also take the value 0, which is typically not the case in some_parameter.

fractional parameter should be defined to also take into account the parameter_ranges of some_parameter, i.e. value_min + [0-1] * (some_parameter - value_min), where some_parameter ranges between value_min and some value_max.