Unidentified variable or function of x

function [x]=cake(p,q,r)

a=diff(p,x)
b=diff(q,x)
c=exp(-1*int(p,x))

p2=diff(((a+b)*c),x)/((a+b)*c)
q2=((a+b*c)*(-c))
r2=(((a+b)*c)*diff(r,x))-((diff(((a+b)*c),x))*((a+b)*c))
end

I am trying to make an algothrism but x variable is unidentified.

Help.

Answer 1

[KSSV]

function x=cake(p,q,x)

a=diff(p,x)
b=diff(q,x)
c=exp(-1*int(p,x))

p2=diff(((a+b)*c),x)/((a+b)*c)
q2=((a+b*c)*(-c))
r2=(((a+b)*c)*diff(r,x))-((diff(((a+b)*c),x))*((a+b)*c))
end