# simplify_full() does not simplify

Hi

```
var('a,b,z')
assume(z,'complex')
assume(a,'real') ;assume(b,'real')
f(a,b,r)=(a^2 + b^2 - sqrt(a^2 + b^2 - r^2) * sqrt(a^2 + b^2) * sqrt((a^2 + b^2 - r^2) / (a^2 + b^2))) / (a - I*b)
show(f)
show(f.simplify_full())
```