Undifined function or variable x

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I am trying to create a matlab function that graphs a particular function in 3D, however I keep getting the error undifined variable or not enough input arguments, Here is my code.

R1 = 2;
R2 = 1;
s1 = [-2;2];
s2 = [3;-1];
n1 = 2;
n2 = 1;
%for values of x and y between -5 and 5
landscape(-5:5, -5:5);
 
function M = landscape(x, y)
   M = H1 + H2;
    function h1 = H1(x, y, R1, s1, n1)
       h1 = (1/(1+(R1/sqrt((x-s1(1))^2+(y-s1(2))^2))^n1));
    end
    function h2 = H2(x, y, R2, s2, n2)
       h2 = (1/(1+(R2/sqrt((x-s2(1))^2+(y-s2(2))^2))^n2));
    end
surf(M)
contour(M)
end
%Thanks 

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Stephen23 2019-10-15

编辑：Stephen23 2019-10-15

在 MATLAB Online 中打开

You defined two nested functions H1 and H2, each with five input arguments:

function h1 = H1(x, y, R1, s1, n1)

then you call those functions withput any input arguments at all:

M = H1 + H2;

The variables R1, s1, n1 are not defined inside landscape.

Dawid Brits 2019-10-15

在 MATLAB Online 中打开

I fixed it up as follows

landscape(x, y, R1, s1, n1, R2, s2, n2)
 
function M = landscape(x, y, R1, s1, n1, R2, s2, n2)
 
  M = H1(x, y, R1, s1, n1) + H2(x, y, R2, s2, n2); 
  
    function h1 = H1(x, y, R1, s1, n1)
       h1 = (1/(1+(R1/sqrt((x-s1(1))^2+(y-s1(2))^2))^n1));
    end
 
    function h2 = H2(x, y, R2, s2, n2)
       h2 = (1/(1+(R2/sqrt((x-s2(1))^2+(y-s2(2))^2))^n2));
    end
 
surf(M)
contour(M)
end

But now it gives my an error about incorrect matrix operation, which I dont understand because Im only calling a single value from the matrix.

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Answer 1

Walter Roberson 2019-10-15

在 MATLAB Online 中打开

0 个投票

function better_homes_and_gardens
    R1 = 2;
    R2 = 1;
    s1 = [-2;2];
    s2 = [3;-1];
    n1 = 2;
    n2 = 1;
    %for values of x and y between -5 and 5
    landscape(-5:5, -5:5);
     
    function M = landscape(x, y)
       M = H1(x, y, R1, s1, n1) + H2(x, y, R2, s2, n2);
        function h1 = H1(x, y, R1, s1, n1)
           h1 = (1./(1+(R1/sqrt((x-s1(1)).^2+(y-s1(2)).^2)).^n1));
        end
        function h2 = H2(x, y, R2, s2, n2)
           h2 = (1./(1+(R2/sqrt((x-s2(1)).^2+(y-s2(2)).^2)).^n2));
        end
        surf(M)
        contour(M)
    end
end

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Dawid Brits 2019-10-15

I added a couple more . s and now it gives me an error relating to M not being a matrix in the surf plot command? What am I doing wrong?

Walter Roberson 2019-10-15

编辑：Walter Roberson 2019-10-15

在 MATLAB Online 中打开

function better_homes_and_gardens
    R1 = 2;
    R2 = 1;
    s1 = [-2;2];
    s2 = [3;-1];
    n1 = 2;
    n2 = 1;
    %for values of x and y between -5 and 5
    landscape(-5:5, -5:5);
     
    function M = landscape(x, y)
       M = H1(x, y, R1, s1, n1) + H2(x, y, R2, s2, n2);
        function h1 = H1(x, y, R1, s1, n1)
           h1 = (1./(1+(R1./sqrt((x-s1(1)).^2+(y(:)-s1(2)).^2)).^n1));
        end
        function h2 = H2(x, y, R2, s2, n2)
           h2 = (1./(1+(R2./sqrt((x-s2(1)).^2+(y(:)-s2(2)).^2)).^n2));
        end
        surfc(M)
    end
end

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