# ApCoCoA-1:NC.Mul

## NC.Mul

Multiplication of two polynomials in a non-commutative polynomial ring.

### Syntax

NC.Mul(F1:LIST, F2:LIST):LIST

### Description

*Please note:* The function(s) explained on this page is/are using the *ApCoCoAServer*. You will have to start the ApCoCoAServer in order to use it/them.

Please set non-commutative polynomial ring (via the command Use) and word ordering (via the function NC.SetOrdering) before calling this function. The default word ordering is the length-lexicographic ordering ("LLEX"). For more information, please check the relevant commands and functions.

@param

*F1, F2:*two non-commutative polynomials, which are left and right operands of multiplication respectively. Each polynomial is represented as a LIST of LISTs, and each element in every inner LIST involves only one indeterminate or none (a constant). For example, the polynomial`f=2x[2]y[1]x[2]^2-9y[2]x[1]^2x[2]^3+5`is represented as F:=[[2x[1],y[1],x[2]^2], [-9y[2],x[1]^2,x[2]^3], [5]]. The zero polynomial`0`is represented as the empty LIST [].@return: a LIST which represents the polynomial equal to

`F1*F2`.

#### Example

USE ZZ/(31)[x[1..2],y[1..2]]; F1:= [[2x[1],x[2]], [13y[2]], [5]]; -- 2x[1]x[2]+13y[2]+5 F2:= [[2y[1],y[2]], [19y[2]], [2]]; -- 2y[1]y[2]+19y[2]+2 NC.Mul(F1,F2); [[4x[1], x[2], y[1], y[2]], [7x[1], x[2], y[2]], [4x[1], x[2]], [-5y[2], y[1], y[2]], [10y[1], y[2]], [-y[2]^2], [-3y[2]], [10]] ------------------------------- NC.Mul(F2,F1); [[4y[1], y[2], x[1], x[2]], [7y[2], x[1], x[2]], [4x[1], x[2]], [-5y[1], y[2]^2], [10y[1], y[2]], [-y[2]^2], [-3y[2]], [10]] ------------------------------- NC.Mul([],F1); [ ] -------------------------------

### See also