# Using an index in a loop as a variable in another function

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Oskar Mevik Päts on 27 Nov 2019
Commented: Oskar Mevik Päts on 27 Nov 2019
function alpha = uppp2(x)
N = 100; d = 75; g = 5; h = 0.1;
for n = 1:x
alpha(1,n) = (x+1-n) * d;
end
for n = 1:N
alpha((n+1),1) = alpha(n,1) + g * h;
end
for j = 2:x
for n = 1:N % index n
alpha(n+1,j) = alpha(n,j) + h * vel((alpha(n,j-1)) - alpha(n,j))
end
end
end
function kappa = vel(y)
kappa(y >= d) = n * h * 25 / 6 % Here i want to use the same index n as in the foor loop
kappa(y == d) = 25
kappa(y <= d) = g - 1
end
% How do I achive this? It seems like the function Kappa doesn't find the variable n.

Johannes Fischer on 27 Nov 2019
Edited: Johannes Fischer on 27 Nov 2019
You need to provide it as an additional argument (the same holds for d, g, and h):
...
alpha(n+1,j) = alpha(n,j) + h * vel(n, d, g, h, (alpha(n,j-1)) - alpha(n,j))
...
function kappa = vel(n, d, g, h, y)
kappa(y >= d) = n * h * 25 / 6 % Here i want to use the same index n as in the foor loop
kappa(y == d) = 25
kappa(y <= d) = g - 1
end
Your 'vel' functions can't access n, d, g and h because they are only defined in uppp2.

#### 1 Comment

Oskar Mevik Päts on 27 Nov 2019
I see, that's the key. Thank you, this bugged me out. Muy appriciated!