symbolically differentiating of a function not to be mixed with other constants

Hi All

I was reading this link here

to derivate symbolically this equation :

p= c1*r +c2/r ;

the problem is that when you write : y=sym('y(t)') ;

then you can not define the function , to derivate and see the result , because it will only be like : diff(p(r), r) ;

but if I write the function as above , how can I make matlan know that r is the variable and the rest are just constants ?

Answer 1

[A Jenkins]

syms r c1 c2
p=c1*r+c2/r 
diff(p,r)
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ans =

c1 - c2/r^2