Index in position 1 is invalid. Array indices must be positive integers or logical values.
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Johannes Pommerening
on 2 Jul 2018
Answered: Abhinav chhabra
on 25 Oct 2021
I got the problem that W is full of NaN's. Error is:
"Index in position 1 is invalid. Array indices must be positive integers or logical values.
Error in Seperationsansatz_2_lin_z (line 16) w(r,t) = W.*T;"
approach A*diff(w,r) + A*r*diff(w,r,r) -B*diff(w,t,t)
rspan = linspace(0,1);
W0 = [0; 1];
[r,W] = ode45(@odefct1,rspan, W0);
tspan = linspace(0,1);
T0 = [0;1];
[t,T] = ode45(@odefct2,tspan,T0);
w(r,t) = W.*T;
% plot(r,W(:,1),'-o',r,W(:,2),'-o')
% title('Solution');
% xlabel('Radius r');
% ylabel('Solution W');
% legend('W_1','W_2')
function dWdr = odefct1(r,W)
E = 70e7;
rho = 2.6989e-4;
ny = 0.34;
K = 1;
A = (0.5-ny);
B = rho*(1-2*ny)*(1+ny)/E;
dWdr = [ W(2); W(1)*(B*K)/A - W(2)/r];
end
function dTdt = odefct2(t,T)
K = 1;
dTdt = [T(2); K*T(1)];
end
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Accepted Answer
KSSV
on 2 Jul 2018
This line:
w(r,t) = W.*T;
Replace with:
w = W.*T;
2 Comments
Dinglie Pang
on 18 Dec 2020
Thanks! It works for my error like this! Btw, what's the theory behind it? I just unitentionally type it like "w(r,t)" and didn't see the difference was made, compared with "w"
KSSV
on 18 Dec 2020
When you use w(r,t).. it means w is an array an you are trying to extract indices r,t. To do this your r, t should be positive integers or logical indices. But this is not the case in present. r, t are not indices, so error. You are not supposed to use w(r,t) here.
More Answers (1)
Abhinav chhabra
on 25 Oct 2021
Close matlab and start again. Its weird but worked for me!
all the best
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