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plot symbolic function real part

Asked by Andrea Giordano on 31 Mar 2019
Latest activity Commented on by Star Strider
on 31 Mar 2019
Hello there,
I would like to plot the real part of this symbolic function I have just solved.
Parameters 'a' and 'e' are varying between 5 and 9, and 0.05 and 0.15 respectively.
Unfortunately, it does not work.
Here you go with my code ( solution is a ratio of sum of Bessel functions of order zero).
clc
clear
set(groot,'DefaultAxesFontSize',14)
set(groot,'DefaultLineLineWidth',1.5)
syms a e
A = [besselj(0,-1i*a*e), bessely(0,-1i*a*e); ...
besselj(0,-1i*a), bessely(0,-1i*a)];
b = [-1; -1];
X = linsolve(A, b);
disp(X)
a = linspace(5,9);
e = linspace(0.05, 0.15);
plot(a, e, X)

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1 Answer

Answer by Star Strider
on 31 Mar 2019
 Accepted Answer

You are plotting a function of two variables, so you need to use a plot that accommodates them, and that your function is symbolic.
Try this:
syms a e
A = [besselj(0,-1i*a*e), bessely(0,-1i*a*e); ...
besselj(0,-1i*a), bessely(0,-1i*a)];
b = [-1; -1];
X = linsolve(A, b);
disp(X)
a = linspace(5,9);
e = linspace(0.05, 0.15);
fsurf(real(X), [5 9, 0.05 0.15])
xlabel('a')
ylabel('e')
Experiment to get the result you want.

  2 Comments

Thank you. Any other options that fsurf that I can try?
regards,
Andrea.
Star Strider
on 31 Mar 2019
As always, my plesure.
There are several 3D plots that will probably work with your system. See the documentation on fcontour (link), fmesh (link), and fplot3 (link).

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