"Igor" wrote in message <firstname.lastname@example.org>... > I cannot provide the whole code, just key components: > > I have system of 16 eq like this(only first rows) for steady state: > ..... > function [c,f,s] = pdex14pde.... > c = ones(NumVars,1);%c > f = [(D_bio+D_O2)*DuDx(1)-w*u(1);.... > s = [(BC0_O2-u(1))*alfax + (-0.25*R8-2* 1.5*R21 - 0.5*R22) - R1*F;... %w,R,alfax-some constant coef. > .......... > function u0 = pdex1ic(~) > global NumVars; > u0 = zeros(NumVars,1);%u0 > ........... > function [pl,ql,pr,qr] = pdex1bc(~,ul,~,ur,~) > pl = [ul(1)-BC0_O2;... > ql = [0;1;.... > pr = [w*ur(1);... > qr = ones.... > > This code takes 300 sec for calculation. > > But then I make some BC0_OM1=(360*cos(t*(2*pi))+360) it takes hours. > > Maybe it will help, > Igor
I doubt that a steady-state solution for your problem exists if a boundary condition depends on time. Or did I misunderstand something ?