Struggling to plot a complex function using the mesh command.

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Wojciech Kalinowski 2020-7-23

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评论： Wojciech Kalinowski 2020-7-23

采纳的回答： KSSV

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Hi,

I need help with making a complex mesh of a function. The function is simply sin(a+a*pi/2) but a is a complex number.

I want to make the domain from -360i to 360i in the complex axis and -360 to 360 in the real axis. With a step of 1 in each. Meaing I will have 721x721 resutls to plot.

upper = 360;
dx = 1;
x = -upper:dx:upper;
z = zeros(length(x),length(x));
y = zeros(1, length(x));
for i = 1:length(x)
    for count = 1:length(x)
        z(i,count) = complex(x(i),x(count));
    end
end
y = sind(z+z.*pi()./2);

Above is the code I used to get the results for the function and stored it in y. x is every point along the real axis, and z is everypoint on the real-imagainary plane.

Now I'm not sure how I should plot this using the mesh function. Of course there is the first problem that plotting this would require 4 dmentions; but I'm happy to take the absolute value/real value/ complex value to limit the answer to 3d. But, I'm not sure how to polt any of these graphs, and ideal plot them all at the same time.

mesh(x , x*j ? , ?)

Thank you in advanced.

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KSSV 2020-7-23

The function has a, and a values are defined......how you can take values from -2*pi to 2*pi. ?

Wojciech Kalinowski 2020-7-23

That's my bad, the a values where an examples. in reality

the a having a fixed set was just me trying to explain the plot in the cooridnet system. So that through every real number, taking a line pependicular to the real axis, there exists a user defined amount of complex numbers. Hence a = 0, i, -i, 1+i, ect.

Sorry that was my bad wording. Will remove the finite set from the question.

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Answer 1

KSSV 2020-7-23

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Try something like this:

ar = linspace(-2*pi,2*pi,10) ; 
[r, c] = meshgrid(ar) ; 
a = r+1i*c ; 
y = sin(a+a*pi/2) ; 
surf(real(a),imag(a),abs(y))

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KSSV 2020-7-23

在 MATLAB Online 中打开

Increase the number in linspace.

n = 100 ; 
ar = linspace(-2*pi,2*pi,n) ; 

Wojciech Kalinowski 2020-7-23

I have, but to have a good resolution to confirm the expected shaped I had to take n to 1000 over a small range. For all other purpose ~200 is fine. Once again thank you.

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