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vpasolve for numerical solution
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Hello I am trying to find a solution to the equation:
1= 0.95*2*invtan(4.5/2*r)*r/(4.5)
for the unknown r that satisfies the equality or comes as close to it as possible
I have tried using vpasolve by entering this into matlab:
syms r
vpasolve(0.95 * 2 * atan((4.5)/(2*r)) * r / (4.5) == 1,r)
but I come up with matlab saying
[ empty sum ]
I want to use matlab to solve this, can anyone help?
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Answers (1)
Mischa Kim
on 12 Jun 2014
Edited: Mischa Kim
on 12 Jun 2014
Richard, it seems the equation you posted cannot be satisfied.
0.95 * 2 * atan((4.5)/(2*r)) * r / (4.5) == 1
or
0.95 * 2 * atan((4.5)/(2*r)) * r / (4.5) - 1 == 0
which I am calling f in the following.
r = -300:0.1:300;
f = 0.95*2*atan((4.5)./(2*r)).*r/4.5 - 1;
plot(r,f)
![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/175085/image.png)
In other words, there is no r for which f = 0.
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