how to change the code below with while loop to for loop?

Question

Nilly 2018-1-17

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/377661-how-to-change-the-code-below-with-while-loop-to-for-loop

回答： Mihir 2023-6-18

I would like to change this while loop to for loop and is there any way to re-code it without mod(c,2500)?

    % code
dx = 1;
x = 0:dx:1000;
x(end) = [];
u = zeros(size(x));
u(x<=220) = 1;
t = 0;
dt = 450;
uinit = u;
k = 0.001;
s = 0.22;
tend = 4000000;
v = s*k;
c = 1;
vmax = 0;
unew(1,:) = uinit;
front1 = 0.75*min(uinit)+0.25*max(uinit);
front2 = 0.25*min(uinit)+0.75*max(uinit);
front = length(uinit([uinit>front1 & uinit<front2])); 
 figure(1)
plot(x,uinit)
hold on
while t < tend
D = k*u;
D = (D([2:end,1])+D)/2;
dudx = (u([2:end,1])-u)/dx;
q = -D.*dudx+u*v;
u = u - dt * (q-q([end,1:end-1]))/dx;
if mod(c,2500)==0
plot(x,u)
unew(end+1,:) = u;
end
front1 = 0.75*min(u)+0.25*max(u);
front2 = 0.25*min(u)+0.75*max(u);
front(end+1) = length(u([u>front1 & u< front2]));
vmax(end+1) = max(k*(s+dudx));
t = t+dt;
c = c+1;
end

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Answer 1

Mihir 2023-6-18

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/377661-how-to-change-the-code-below-with-while-loop-to-for-loop#answer_1258134

Hi, the replacement of the outer while loop by the for loop can be made by firstly declaring the upperbound of the for loop (num_plots) in the below code and for replacing the inner if condition, you can write one more for loop the runs for 2500 times. So basically nested for loops will meet the requirements.

num_plots = floor(tend / dt / 2500);

for plot_index = 1:num_plots

for c = 1:2500

Perform the operations here

end

plot(x,u)

unew(end+1,:) = u;

end