Add modulo to function field element

[Saher-Amasha]

a function that takes as input a polynomial.
the function returns the the current polynomial modulo the polynomial given as input

Component: algebra

Reviewer: Dave Morris

Issue created by migration from https://trac.sagemath.org/ticket/31244

[DaveWitteMorris]

comment:1

I don't understand the need for this function, because sage's "modulo" operator % works for polynomials:

sage: Qx.<x> = QQ[x]                                                                           
sage: (5*x^4 + 4*x^3 + 3*x^2 + 2*x + 1) % x^2                                                  
2*x + 1

[Saher-Amasha]

comment:2

Replying to @DaveWitteMorris:

I don't understand the need for this function, because sage's "modulo" operator % works for polynomials:

sage: Qx.<x> = QQ[x]                                                                           
sage: (5*x^4 + 4*x^3 + 3*x^2 + 2*x + 1) % x^2                                                  
2*x + 1

the modulo operator doesn't work in this example

sage: FF.<t> = FunctionField(QQ)                                                
sage: f= t^3+t^2+1 ;f                                                           
t^3 + t^2 + 1
sage: g= t^2+ 1 ;g                                                              
t^2 + 1
sage: f%g   
sage: f.mod(g) 

the % operator returns an error

the function mod ( f.mod(g) ) always returns zero regardless of f and g

thanks for taking the time to respond

[DaveWitteMorris]

comment:3

0 is the correct answer for f.mod(g) (unless g = 0), because 1/g is in FF.

However, perhaps it would make sense to have a polynomial method that returns f.numerator() if f is a polynomial (and gives a ValueError otherwise). This would allow a user to treat f as a polynomial. For example, they could write f.polynomial() % g.polynomial() or f.polynomial().mod(g.polynomial()).

[mkoeppe]

comment:4

Setting new milestone based on a cursory review of ticket status, priority, and last modification date.

[Saher-Amasha]

comment:5

please remove ticket, function already exists.

[DaveWitteMorris]

Reviewer: Dave Morris

[DaveWitteMorris]

comment:7

OK, we can close this ticket as invalid.

[mkoeppe]

Changed author from Saher Amasha ,Safa Amasha to none