HELP needed! (Error using surf, Z must be a matrix, not a scalar or vector)
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Hi guys,
I'm quite new to matlab and I'm required to plot this paraboloid graph. I have spend hours trying to solve but no result. Don't think it's a matter of cap's as well.
A= 1./1500;
X_r2 = 1;
Z_r2 = 0;
x = -10:.1:10;
y = -10:.1:10;
[X,Y] = meshgrid(x,y);
syms A X Y Z X_r2 Z_r2
Temp_Z = solve(sqrt((X-X_r2).^2 + Y.^2 + (Z-Z_r2).^2) - sqrt(X.^2 + Y.^2 + Z.^2) - A == 0 , Z );
Z = Temp_Z;
surf(X,Y,Z)
Please help!
4 个评论
Thomas
2013-10-4
You are overwriting your meshgrid matrices with symbolic vars
syms A X Y Z X_r2 Z_r2
...?
回答(3 个)
cr
2013-10-5
Whoa, I think thats not quite what you want to do. What is the eqn you want to plot? If i'm plotting the eqn z = sin(sqrt(x^2+y^2))/sqrt(x^2+y^2), this is what I do:
a = -10:.1:10;
b=a;
[x,y] = meshgrid(a,b);
z = sin(sqrt(x.^2+y.^2))./sqrt(x.^2+y.^2);
surf(x,y,z)
cr
2013-10-7
ok, that clarifies that you need to use solve. if solve function is giving you a closed form solution for your eqn, use subs to substitute for various values of x & y inside two loops. Or better, manipulate the result you get to vectorize it so that you can use meshgrid matrices. Then comes surf.
0 个评论
Walter Roberson
2013-10-7
After you solve(), use matlabFunction() to convert the symbolic form to an anonymous function. You can then apply that to the meshgrid matrices.
There are going to be at least two solutions for each point. You need to select one of them or separate out the two parts before doing the matlabFunction()
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