help with contour plot
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Trying to plot.
The equation is:
A tip in polar coordinates:
And my code:
(The picture above is how it is supposed to look9
1 个评论
Walter Roberson
2020-4-29
Note that volunteers are seldom interested in typing in code from pictures of code. Make it easier for the volunteers by providing actual code.
回答（1 个）
Walter Roberson
2020-4-29
Your line with == computes whether each element of Z happens to have a particular and exact relationship to X and Y. Once it has done that computation of whether there is a match or not, your code then throws away that computation, having wasted time but otherwise not having done anything useful.
I would suggest to you,
Z2 = X.^2 + Y.^2 + 1;
surf(X, Y, Z2)
4 个评论
Hanna Sundling
2020-4-29
I changed as you suggested but the biggest problem is that when I plot is that I only get this:
And not the full object, and I do not know why.
Walter Roberson
2020-4-29
Your sample diagram has negative Z values. Your suggested code of surf(X, Y, Z.^2) has only positive Z (unless Z includes values with purely imaginary components. You need to go back and decide whether using X, Y, Z^2 is correct surfing.
Hint: if P^2 = something, then it implies that P of both +sqrt(something) and -sqrt(something) are valid.
Hanna Sundling
2020-4-29
Walter Roberson
2020-4-29
surf() one thing. "hold on". surf() another thing that is mirror in Z.
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2020-4-29
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2021-8-20
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