How to check a value in a loop at a certain instance?

Question

Westin Messer 2018-11-27

0
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https://ww2.mathworks.cn/matlabcentral/answers/432381-how-to-check-a-value-in-a-loop-at-a-certain-instance

评论： Cris LaPierre 2018-11-28

I want to know what the value of u and v are when t = 7. Does anyone know how I'd do that?

close all;
clear all;
a = 0;
b = 20;
nel = 200; % number of elements
h = (b-a)/nel; % step size
nv = nel+1;% number of vertices
x = a:h:b; % mesh
dt = 0.001; % time steps
tend = 20; 
e=ones(nv, 1);
%Discretization of the Laplace operator
Delta=1/(h^2)*spdiags([e -2*e e], -1:1, nv, nv);
Delta(1,2) = 2/h^2;
Delta(end,end-1) = -2/h^2;
% parameters of the model
eps = 0.01;
alpha = 0.1; %0.22 - max 
beta = 0.2; % determines the width of the pulse
gamma = 0.25 * beta; % determines the shape of the pulse
D =2;
% Max D = 8;
% Min D = 1.7;
% initial guess
u = 0.5 * (x < 3);
v = 0 * x;
counter = 1;
% explicit Euler scheme
g=dt:dt:tend;
for t=dt:dt:tend
    
    u = u + dt * eps* (D*((Delta * u')')) +  dt/eps * (u .* (1 -u ).*(u-alpha) - v);
    v = v + dt * (gamma * u - beta * v);
end