string("Model1: Apply constrained nonlinear optimization on the diffusivity, volume fractions and their sum.\n\t\t\tReturn n fanning angle estimates, using the Hessian of the cost function"),
false,no_argument),
gridsearch(string("--gridsearch"),false,
string("Use grid search (on the fanning eigenvalues). Default=off"),
false,no_argument),
use_f0(string("--f0"),false,
string("\tInclude noise floor parameter in the model"),