There is an error in call the function file

Question

yogeshwari patel 2023-6-4

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1977879-there-is-an-error-in-call-the-function-file

评论： Walter Roberson 2023-6-4

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

1 个评论
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KALYAN ACHARJYA 2023-6-4

f in the function?

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Answer 1

Star Strider 2023-6-4

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1977879-there-is-an-error-in-call-the-function-file#answer_1249844

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.

5 个评论
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Walter Roberson 2023-6-4

在 MATLAB Online 中打开

fluxfunction([8 1 5],[9 3 -1])
Not enough input arguments.

Error in solution>f (line 7)
    V = exp(-t)*sin(pi*x)*(pi^2-1);

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

Walter Roberson 2023-6-4

在 MATLAB Online 中打开

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.

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