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Error using Quiver function

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Bajinder Singh
Bajinder Singh on 19 Sep 2020
Commented: Bajinder Singh on 19 Sep 2020
Hi, I am having an error using Quiver. Below is my code.
[X,Y] = meshgrid(-1:0.1:1, -1:0.1:1);
syms U_inf Lambda Psi X Y u v
Psi = U_inf*Y+((Lambda/k)*atan(Y/X));
u = diff(Psi,Y);
v = diff (Psi, X);
quiver (X,Y,u,v)
The error is "Unable to convert expression into double array."
I believe I am not using the syms correctly. Any help is appreciated!


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Answers (1)

KSSV on 19 Sep 2020
You cannot use like that. You need to take all data in double i.e in numbers to plot the arrows.Something like below:
[X,Y] = meshgrid(-1:0.1:1, -1:0.1:1);
U_inf = rand ; % define your value
Lambda = 1. ; %define your value
Psi = U_inf*Y+((Lambda/k)*atan(Y./X));
u = gradient(Psi);
v = gradient(Psi);
quiver (X,Y,u,v)

  1 Comment

Bajinder Singh
Bajinder Singh on 19 Sep 2020
Thanks for the response. But I am not given any values for U_inf and Lambda. They are simply constants. That is why I was trying to use the "syms" command.

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