# There is an error in call the function file

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function V = fluxfunction(a,b)

% Godunov

V = max(f(max(a,0)),f(min(b,0)));

end

%%%%%%%%%%%%%%%%%%

% Godunov Scheme

% ut + (u^2/2)x = eps*uxx;

x0 = 0;

xf = 5;

N = 100;

h = (xf-x0)/N;

eps = 0.01;

delt = 0.5*h;

lambda = delt/h;

mu = delt/(h^2);

t0 = 0;

tf = 5;

x = zeros(N-1,1);

u0 = zeros(N-1,1);

for j=1:N-1

x(j) = x0+j*h;

if(x(j) < 1)

u0(j) = sin(pi*x(j));

end

if(x(j) > 1)

u0(j) = 0;

end

end

M = fix((tf-t0)/delt);

unew = zeros(N-1,1);

t = t0;

for k=1:M

unew(1) = u0(1) - lambda*(fluxfunction(u0(1),u0(2)) - fluxfunction(0,u0(1))) + mu*eps*(u0(2) - 2*u0(1) + 0);

unew(N-1) = u0(N-1) - lambda*(fluxfunction(u0(N-1),0) - fluxfunction(u0(N-2),u0(N-1))) + mu*eps*(u0(N-2) - 2*u0(N-1) + 0);

for j=2:N-2

unew(j) = u0(j) - lambda*(fluxfunction(u0(j),u0(j+1)) - fluxfunction(u0(j-1),u0(j))) + mu*eps*(u0(j+1) - 2*u0(j) + u0(j-1));

end

plot(x,unew)

title('Godunov Scheme');

ylim([0,1]);

pause(0.01);

u0 = unew;

t = t+delt;

end

ugod = unew;

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%Error %%%%%%%%%%%%%%%%%%%%%

Not enough input arguments.

Error in f (line 3)

V = exp(-t)*sin(pi*x)*(pi^2-1);

Error in fluxfunction

V = max(f(max(a,0)),f(min(b,0)));

Error in Godnov

### Answers (1)

Star Strider
on 4 Jun 2023

##### 5 Comments

Walter Roberson
on 4 Jun 2023

fluxfunction([8 1 5],[9 3 -1])

function V = fluxfunction(a,b)

V = max(f(max(a,0)),f(min(b,0)));

end

function V = f(x,t)

V = exp(-t)*sin(pi*x)*(pi^2-1);

end

Walter Roberson
on 4 Jun 2023

fluxfunction()

function V = fluxfunction(a,b)

V = max(f(max(a,0)),f(min(b,0)));

end

function V = f(x,t)

V = exp(-t)*sin(pi*x)*(pi^2-1);

end

Observe that if not enough inputs are passed to fuxfunction so the parameters to f cannot be evaluated, then the error is reported in fluxfunction, whereas if enough parameters are passed to fluxfunction but not enough are passed to f, then the error is reported in f.

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