MATLAB: Extract x and y coordinates for points in a multivariable function

functionsmultivariablexygridxyz

I have a function of two variables(x and y). This function only has values of 0 and 1 for each point on the x-y grid. How would I extract the x,y location on the grid for the values which are 1? Thanks

Best Answer

Given a z

[i,j]=find(z);  % indices for lookup into x,y

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MATLAB: Plotting Multivariable function poltting

[X,Y] = meshgrid(1:.2:10);                                
Z =(X*Y) / (X^2 + Y^2);
surf(X,Y,Z)

You should avoid including 0 within the grid boundary since it creates a singularity.

MATLAB: Meshgrid multi-valued function data

You should use hold on to plot multiple parts. The code below is a fix to your code.

radius=3;
x = linspace(-radius,radius,100);
y = linspace(-radius,radius,100);
[X,Y] = meshgrid(x,y);
Z = sqrt(radius^2 - X.^2 - Y.^2);
Z(imag(Z)~= 0) = 0 ;
%set coordinates outside of the sphere to the edge
L=(X.^2+Y.^2)>(radius^2);
phi=atan2(Y,X);
X(L)=radius*cos(phi(L));
Y(L)=radius*sin(phi(L));
%put the two halves together
Z = [Z,-Z];
X = [X,X];
Y = [Y,Y];
figure(1),clf(1)
surf(X,Y,Z)

Best Answer

Related Solutions

MATLAB: Plotting Multivariable function poltting

MATLAB: Meshgrid multi-valued function data

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