Contour plot of a function

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University Glasgow 2022-9-1

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评论： Torsten 2022-9-1

Please someone should with a contour plot of a p for various values of xi and H. For instance, H=0..3, and xi=2.0..0.0, where H is the x-axis, xi is the y-axis and p is the height of the contour. I need r to compute p, that is why write the expression for r.

for i = 1:m

q = x +i*y;

r(i)=q-(1-alpha)*tan(q)+(alpha3*xi*alpha/eta1)./(4*k1*q.^2/d^2-alpha3*xi/eta1).*tan(q)...

+ ((chi_a*H.^2*alpha)./(4*k1*q.^2/d^2-alpha3*xi/eta1 - chi_a*H.^2)).*tan(q);

end

for i=1:m

p(i) = gamma1*alpha/(4*k1*(r(i).^2)/d^2-alpha3*xi/eta1);

end

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回答（1 个）

Torsten 2022-9-1

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编辑：Torsten 2022-9-1

在 MATLAB Online 中打开

H = 0:0.01:3;
XI = 0:0.01:2;
for i=1:numel(H)
  h = H(i);
  for j=1:numel(XI)
    xi = XI(j);
    for k=1:m
      q = x +k*y;
      r = q-(1-alpha)*tan(q)+(alpha3*xi*alpha/eta1)./(4*k1*q.^2/d^2-alpha3*xi/eta1).*tan(q)...
          + ((chi_a*H.^2*alpha)./(4*k1*q.^2/d^2-alpha3*xi/eta1 - chi_a*H.^2)).*tan(q);
      p(i,j,k) = gamma1*alpha/(4*k1*(r^2)/d^2-alpha3*xi/eta1);
    end
  end
end

Now p is 3-dimensional instead of 2-dimensional as required for a contour plot. What now ?

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Torsten 2022-9-1

So you have x1, x2, H and xi given over an interval of values and thus r (resp. p) depending on 4 parameters. If you want to plot a surface over H and xi, you must set x1 and x2 to a constant value and do the same for H and xi what you did for x1 and x2 in your code from above.