# Code not working, something with while loop

1 view (last 30 days)
Zach Harrison on 16 Apr 2021
Commented: Zach Harrison on 16 Apr 2021
I think the error in my code is in the while loop, I don't think i and/or j are increasing their value.
E_n is the value that will give my my answer. I want i and j to start at 1, but when I do, E_n is 0 for all values. Then when I change the starting conditions, only a few numbers are non-zero, and they are all the same value. This is why I think my while loops are not working, which leads to my code not checking every element in the matrix M.
M_0 = [0, 30, 90, 135, 180, 200, 350;
0, 30, 90, 135, 180, 200, 350;
0, 30, 90, 135, 180, 200, 350;
0, 30, 90, 135, 180, 200, 350];
M = M_0 .* (pi / 180);
e = [0.01;
0.1;
0.5;
0.9];
% Initial Calculations
E = zeros(4,7);
error = 10;
i = 1;
j = 1;
while j <= 4
while i <= 7
if M(j,i) > -pi && M(j,i) < 0
E_n = M(j,i) - e(j);
elseif M(j,i) > pi
E_n = M(j,i) - e(j);
elseif M(j,i) < pi && M(j,i) > 0
E_n = M(j,i) + e(j);
else
E_n = M(j,i);
end
while error >= 10^-6
E_n_plus_1 = E_n + ((M(j,i) - E_n + e(j) * sin(E_n)) / (1 - e(j) * cos(E_n)));
error = abs(E_n - E_n_plus_1);
E_n = E_n_plus_1;
end
E(j,i) = E_n_plus_1;
i = i + 1;
end
j = j + 1;
end
M_deg = reshape(M_0,28,1);
E_deg = reshape(E,28,1);
e1 = [0.01;0.01;0.01;0.01;0.01;0.01;0.01;
0.1;0.1;0.1;0.1;0.1;0.1;0.1;
0.5;0.5;0.5;0.5;0.5;0.5;0.5;
0.9;0.9;0.9;0.9;0.9;0.9;0.9];
table(M_deg,e1,E_deg)
Zach Harrison on 16 Apr 2021
Update: i and j values are 8 and 5 respectively and the end of the code so I guess that part works fine

David Fletcher on 16 Apr 2021
Edited: David Fletcher on 16 Apr 2021
The counter for the inner i loop never gets reset back to it's initial value, so it will only run on the first iteration of the j loop. You will incidentally have the same problem with the error loop, as that never gets re-initialised after the loop either
Zach Harrison on 16 Apr 2021
Thank you, that worked