# Numerically solving 2 coupled PDEs

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1. Aug 17, 2015

### niha1794

I want to solve a system of 2 coupled pde (in MATLAB) of the format:

c1*(df/dt)+c2*(df/dz)+c3*(f)+c4*(g)=0

(dg/dt)=c5*f+c6*g

with Initial conditions as
f(0,t)=1, g(z,0)=0 and f(z,0)=0

0<f,g,z,t<1

I tried using the MATLAB function pdepe to do this but got errors and if I go for numerical solving by finite difference method I get the value of f>1 which is not possible.

If you get values outside of the expected range you better check the values of the coefficients $c_i$ and the stability of the numerical method due to the choosen spatial and temporal steps $\Delta z$ and $\Delta t$, respectively.