# There is an error in call the function file

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yogeshwari patel on 4 Jun 2023
Commented: Walter Roberson on 4 Jun 2023
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
KALYAN ACHARJYA on 4 Jun 2023
f in the function?

Star Strider on 4 Jun 2023
You need to call ‘fluxfunction’ from a script with specific values for ‘a’ and ‘b’ that already existing in the script workspace. You cannot run it by clicking on the green ‘Run’ arrow in the Editor or by running it from the Command Window as you would a script, without supplying apppropriate values for the arguments.
Walter Roberson on 4 Jun 2023
fluxfunction()
Not enough input arguments.

Error in solution>fluxfunction (line 4)
V = max(f(max(a,0)),f(min(b,0)));
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.