function [eps_out,strat_out] = vary_layers(eps_strat,strat)
%varies layer thicknesses and compositions of given layering sequence

strat_out = strat + ((strat./3) .* randn(size(strat)));
strat_out(strat_out<0) = 0;
strat_out = 100 .* (strat_out./sum(strat_out));

eps_changes = 0.25.*randn(size(eps_strat));
eps_strat(eps_strat>3.15) = eps_strat(eps_strat>3.15) + eps_changes(eps_strat>3.15);
eps_out = eps_strat;

end