Spatial discretization has failed

m = 0;

x = 0:0.5:5; %linspace x

t = 0:0.5:100; %linspace t

sol = pdepe(m,@pdex4pde,@pdex4ic,@pdex4bc,x,t); %solver

A = sol(:,:,1);

H = sol(:,:,2);

figure

surf(x,t,A)

title('A(x,t)')

xlabel('Distance x')

ylabel('Time t')

figure

surf(x,t,H)

title('H(x,t)')

xlabel('Distance x')

ylabel('Time t')

-----------------

function [c,f,s] = pdex4pde(x,t,u,DuDx)

R=25;

Q=2.5;

P=56.25;

c = [1; 1];

f = [1; P] .* DuDx;

s = [1+u(1)^2/u(2)-u(1); Q*(u(1)^2-u(2))];

-----------------------------------------

function [Al,Hl,Ar,Hr] = pdex4bc(xl,ul,xr,ur,t)

Al = [0; ul(1)];

Hl = [0; ul(2)];

Ar = [0; ur(1)];

Hr = [0; ur(2)];

----------------

function u0 = pdex4ic(x);
u0 = [13; 338];

I got this message:

Error using pdepe (line 293)
Spatial discretization has failed. Discretization supports only
parabolic and elliptic equations, with flux term involving spatial
derivative.

Error in testp2 (line 4)
sol = pdepe(m,@pdex4pde,@pdex4ic,@pdex4bc,x,t); %solver

Answer 1

[Torsten]

You only set two (strange) boundary conditions instead of four required by the solver.

What are your boundary conditions in mathematical notation ?

Best wishes

Torsten.