# Changing from PolynomialRing to LaurentPolynomialRing and maybe back

Hej,

I am doing some calculations in a Polynomial Ring R<x,y,z> over a finite field GF(p). With the results from that calculation, I would like to do calculations for which I need a Laurent polynomials over the same finite field, how do I do that in SageMath?

```
R=PolynomialRing(GF(field),x,num_var, order='degrevlex')
d=f(x,y,z)
Change to LaurentPolynomialRing
Do so more calculations with results d
```

Thanks