Empty sym: 0-by-1

I am really really new to matlab and essentially just playing around with it. However, I have come across an issue that I am not fully sure how to resolve.

My code is incredibly simple:

syms R
X = 3; 

h1 = .5 - [.25 - (1/4*(R^2))*((R^2)-.0625)]^(1/2) == 5;
solve(h1,R) 

However, when I try to solve h1 when it equals any value other than zero, I get the error - Empty sym: 0-by-1. Can anyone explain to me why this is happening?

Answer 1

[Marco Riani]

First of all it is necessary to replace [ ] with ( ) in your equation.

h1= .5 - (.25 - (1/4*(R^2))*((R^2)-.0625))^(1/2) == 5;
solve(h1,R)

Finally, If you try to plot your equation

x=-200:0.1:200;
y=.5 - (.25 - (1/4*(x.^2)).*((x.^2)-.0625)).^(1/2) -5;
plot(x,y)

you can see that y is never 0

Hope it helps

[Walter Roberson]

It is not necessary to replace the [] with (), but the code is more efficient if you do use ()