### 2.12.15 Normal form for rational fractions : `ratnormal`

`ratnormal` rewrites an expression using it’s irreductible representation. The expression is viewed as a multivariate rational fraction with coefficients in ℚ (or ℚ[i]). The variables are generalized identifiers which are assumed to be algebraically independant. Unlike with `normal`, an algebraic extension is considered as a generalized identifier. Therefore `ratnormal` is faster but might miss some simplifications if the expression contains radicals or algebraically dependant transcendental functions.
Input :

`ratnormal((x```^```3-1)/(x```^```2-1))`

Output :

`(x```^```2+x+1)/(x+1)`

Input :

`ratnormal((-2x```^```3+3x```^```2+5x-6)/(x```^```2-2x+1))`

Output :

`(-2*x```^```2+x+6)/(x-1)`