on 11 Oct 2018

### Bibigul (view profile)

on 14 Oct 2018
Hello, I am working on unsteady 2D coupled PDE. I have four equations need to solve simultaneously. I generate a code even working well. But for accuracy purpose, I need to add tolerance. I did it for 2D (steady case) but couldn't success for this problem. My problem have four unknowns C,T,U and V. 'i' for x-index, 'j' for y-index and 'k' for time level. I am calculating each unknown, say C, at a particular 'i' for all 'j' at '(k+1)th' time level.
I attached my code here. Can someone help me?
Kind regards,
BibiGul

on 11 Oct 2018
Edited by KSSV

### KSSV (view profile)

on 11 Oct 2018

Take the required errors out from the function...run the function for different values of (nx,ny,nt) when you get satisfactory error, break the loop.
nx = 10:10:100 ; % take your desired values
ny = nx ;
nt = nx ;
for i = 1:length(nx)
err = thesisp3atitol2(nx(i),ny(i),nt(i)) ;
if err<=tol
[nx(i) ny(i) nt(i)] % pick these values for less error
break
end
end

Bibigul

### Bibigul (view profile)

on 11 Oct 2018
@KSSV nx, ny and nt are the no of points in x,y direction and for time respectively. Unknown vector , say C, is a vector of size(ny-1,1) for each i. I am calculating C at (k+1)th time level. I am trying to insert while loop.
KSSV

### KSSV (view profile)

on 11 Oct 2018
Yes I know that (nx,ny,nt) are number of points..okay you can replace the for loop with while loop very much.