MATLAB Answers

## how can I write c,f,s in pde function?

Asked by Shangeetha Mahendran

### Shangeetha Mahendran (view profile)

on 20 Dec 2018
Latest activity Edited by madhan ravi

### madhan ravi (view profile)

on 20 Dec 2018
if c is changing with x then how to write f and s
function [c,f,s]= pdefun1(x,z,u,DuDx)
c = (2*U_a/D_s)*(1-x.^2/R1^2); %%% HERE c is changing with x
f = DuDx;
s=0;
end
%%
function u0 = pdeic1(x)
u0 =20;
end
%%
function [pl,ql,pr,qr] = pdebc1(xl,ul,xr,ur,z)
pl=0;
ql=1;
pr=0.6*u0;
qr=1;
end

Torsten

### Torsten (view profile)

on 20 Dec 2018
No, you have to return a scalar value for c, i.e. c evaluated at x,z,u and DuDx (where all of these input parameters are scalars in your case).
Thus you could also write
c = (2*U_a/D_s)*(1-(x/R1)^2);
Shangeetha Mahendran

on 20 Dec 2018
thank you
madhan ravi

### madhan ravi (view profile)

on 20 Dec 2018
@Torsten please post it as an answer so that it would be helpful for many on how to solve pdes properly.

Sign in to comment.

R2017b