function F=finitial(x,s1conc)
% try to find the steady state initial spectrum consistent with
% the s1conc, the concentration in the first section
% x will have nsect -1 values

xx=[s1conc;x/1e7];      % have to de scale, add first section conc
FF=simpcoagr(0,xx);
F=FF(2:end)*1e7;        % rescale
