my while statement wont work

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Brody Wagner
Brody Wagner on 4 Nov 2021
Edited: Chris on 5 Nov 2021
I am attempting to create a temperature field with one set boundary condition and a wire in one corner of my matrix. To populate the matrix i have been using while loops but only the first one is working. In need of some advice.
clc;clearvars;close all;
H=0.5; %Height in mm
W=2; %Width in mm
Nh=50; %number of elements in y axis
Nw=200; %number of elements in x axis
dx=W/Nw; %increment size in x
dy=H/Nh; %increment size in y
%discretizing
x=0:dx:W;
y=0:dy:H;
%
Err=1; %initial error
Tol=1e-3; %Error tolerance
T=zeros([50,200]);
%Boundary Conditions
Tt=20; %This is correct
T(1,1:Nw)=Tt;
C=35;
T(26:end,1)=C;
T(27:end,2)=C;
T(28:end,3)=C;
T(29:end,4)=C;
T(30:end,5)=C;
T(31:end,6)=C;
T(32:end,7)=C;
T(33:end,8)=C;
T(34:end,9)=C;
T(35:end,10)=C;
T(36:end,11)=C;
T(37:end,12)=C;
T(38:end,13)=C;
T(39:end,14)=C;
T(40:end,15)=C;
T(41:end,16)=C;
T(42:end,17)=C;
T(43:end,18)=C;
T(44:end,19)=C;
T(45:end,20)=C;
T(46:end,21)=C;
T(47:end,22)=C;
T(48:end,23)=C;
T(49:end,24)=C;
T(50:end,25)=C;
while Err>Tol
Told=T;
for ii= 2:Nh-25
for jj= 1
T(ii,jj)=(T(ii-1,jj)+(2*T(ii+1,jj))+T(ii,jj+1))/4;
end
end
Err=max(max(abs(T-Told)./T))*100;
%mesh(T),colorbar;colormap;drawnow;
end
while Err>Tol
Told=T;
for q= 50
for r= 26:Nw-1
T(q,r)=((2*T(q,r-1))+T(q-1,r)+T(q,r+1))/4;
end
end
Err=max(max(abs(T-Told)./T))*100;
%mesh(T),colorbar;colormap;drawnow;
end
% below is not working for some reason, should be the same values as the first
% while loop
while Err>Tol
Told=T;
for l= 2:Nh-1
for p= Nw
T(l,p)=((2*T(l,p-1))+T(l-1,p)+T(l+1,p))/4;
end
end
Err=max(max(abs(T-Told)./T))*100;
%mesh(T),colorbar;colormap;drawnow;
end
while Err>Tol
Told=T;
for k= 2:Nh-1
for u= 2:Nw-1
T(k,u)=(T(k+1,u)+T(k,u+1)+T(k-1,u)+T(k,u-1))/4;
end
end
Err=max(max(abs(T-Told)./T))*100;
%mesh(T),colorbar;colormap;drawnow;
end

Answers (1)

Chris
Chris on 4 Nov 2021
Edited: Chris on 5 Nov 2021
It looks like you need to reset Err to 1 after a loop completes.

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