Index in position 1 is invalid. Array indices must be positive integers or logical values.

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

Answer 1

[KSSV]

This line:

w(r,t) = W.*T;

Replace with:

w = W.*T;

[Dinglie Pang]

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]

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.

Answer 2

[Abhinav chhabra]

Close matlab and start again. Its weird but worked for me!

all the best