Comparison with astromodels

[giacomov]

The format I am designing for astromodels to specify functions is very similar to what you are trying to achieve, so maybe we can try to converge. This is what I have:

powerlaw:

    description : 

        A simple power-law with normalization expressed as 
        a logarithm

    formula :

        expression : 10**logK * (x / piv)**index

        latex :

            \frac{dN}{dx} = 10^{logK}~\frac{x}{piv}^{index}

    parameters:

        logK :

            desc : Logarithm of normalization
            initial value : 0
            min : -40
            max : 40

        piv :

            desc : Pivot energy
            initial value : 1
            fix : yes

        index :

            desc : Photon index
            initial value : -2
            min : -10
            max : 10

powerlaw_flux:

    description:

        A simple power-law with the integral between two extremes as 
        normalization parameter

    formula:

        expression : 10**(logK) * (index + 1) * (x / piv)**index / 
                     ( xmin**(index+1) - xmax**(index+1) )

        latex :

            \frac{dN}{dx} = \frac{index + 1}{xmin^{index+1} - xmax^{index+1}}
                            10^{logK}~\frac{x}{piv}^{index} 

    parameters:

        logK :

            desc : Logarithm of normalization
            initial value : 0
            min : -40
            max : 40

        piv :

            desc : Pivot energy
            initial value : 1
            fix : yes

        index :

            desc : Photon index
            initial value : -2
            min : -10
            max : 10

        xmin :

            desc : Lower bound of integration
            initial value : 1

        xmax :

            desc : Upper bound of integration
            initial value : 10

This can easily be read from python as:

import yaml

with open("astromodels/functions/powerlaw.yaml","r") as f:
    d = yaml.load(f)

print(d['powerlaw'])
'A simple power-law with normalization expressed as a logarithm'

print(d['powerlaw']['parameters']['index'])
{'max': 10, 'initial value': -2, 'desc': 'Photon index', 'min': -10}

Maybe we can analyze our respective trials and merge the good things about both in one format.