C++ to Matlab Quick Help

IF I had some C++ that looked like:

Double_t fitfun(Double_t *x, Double_t *p)
{

const Double_t sigintr2     = 12.8*12.8;   // %^2
const Double_t sigelec2     = p[0]*p[0];
const Double_t G            = diethorn(x[0])/diethorn(2100.);
const Double_t out          = TMath::Sqrt(p[1]*p[1]+sigintr2+sigelec2/G/G);
return out;

}

What would be the significance/translation of this? I feel liek it does a fit.. I have a function which calculates that diethorn (parameter) for use in that third line which looks like:

function G = diethornPar(V)
delV = 26.7; % volts
E_min =38.3e3; % volts(/m?)
a = 25.0e-4; % cm
lam_2pi = (V*0.735-73)/2/pi;
lnG = log(2)*lam_2pi/delV*log(lam_2pi/a/E_min);
G = exp(lnG);
end;

If this is too detailed that's ok.

Thanks for your time, Michael