ApCoCoA-1:Weyl.WMul

Weyl.WMul

Computes the product F*G of Weyl polynomial F and G in normal form.

Syntax

```Weyl.WMul(F:POLY,G:POLY):POLY
```

Description

This method multiplies two Weyl polynomials F and G and returns F*G as a Weyl polynomial in normal form.

• @param F A Weyl polynomial.

• @param G A Weyl polynomial.

• @return The product F*G in normal form.

Example

```A1::=QQ[x,d];	--Define appropriate ring
Use A1;
F:=x; G:=d;
Weyl.WMul(F,G);
xd
-------------------------------
Weyl.WeylMul(G,F);
xd + 1
-------------------------------
Weyl.WMul(Weyl.WMul(G,F)-2G,F^3+G);
x^4d - 2x^3d + 4x^3 + xd^2 - 6x^2 - 2d^2 + d
-------------------------------
If you want to multiply Weyl polynomials that are not in normal form say for example F=d^2x^3-2dx^2+7 and G=2d^3x-5xd+3, then
first convert them into normal form before multiplication.
-------------------------------
F:=Weyl.WNormalForm([[d^2,x^3],[-2d,x^2],[7]]);
F;
x^3d^2 + 4x^2d + 2x + 7
-------------------------------
G:=Weyl.WNormalForm([[2d^3,x],[-5x,d],[3]]);
G;
2xd^3 - 5xd + 6d^2 + 3
-------------------------------
Weyl.WMul(F,G);
2x^4d^5 - 5x^4d^3 + 18x^3d^4 - 27x^3d^2 + 36x^2d^3 + 14xd^3 - 18x^2d + 12xd^2 - 35xd + 42d^2 + 6x + 21
-------------------------------
Weyl.WMul(G,F);
2x^4d^5 - 5x^4d^3 + 32x^3d^4 - 32x^3d^2 + 148x^2d^3 + 14xd^3 - 38x^2d + 216xd^2 - 35xd + 42d^2 - 4x + 72d + 21
-------------------------------
Weyl.WMul(Weyl.WNormalForm([[d^2,x^3],[-2d,x^2],[7]]),Weyl.WNormalForm([[2d^3,x],[-5x,d],[3]]));
2x^4d^5 - 5x^4d^3 + 18x^3d^4 - 27x^3d^2 + 36x^2d^3 + 14xd^3 - 18x^2d + 12xd^2 - 35xd + 42d^2 + 6x + 21
-------------------------------

```

Example

```A2::=ZZ/(101)[x[1..2],y[1..2]];
Use A2;
Weyl.WMul(x[1]^11,y[1]^11);
x[1]^11y[1]^11
-------------------------------
Weyl.WMul(y[1]^11,x[1]^11);
x[1]^11y[1]^11 + 20x[1]^10y[1]^10 - 10x[1]^9y[1]^9 + 33x[1]^8y[1]^8 + 23x[1]^7y[1]^7 - 17x[1]^6y[1]^6 - x[1]^5y[1]^5 -
18x[1]^4y[1]^4 - 36x[1]^3y[1]^3 - 36x[1]^2y[1]^2 + 26x[1]y[1] - 16

-------------------------------
Weyl.WMul(y[1]^21,x[1]^21);
x[1]^21y[1]^21 + 37x[1]^20y[1]^20 + 27x[1]^19y[1]^19 + 17x[1]^18y[1]^18 - 37x[1]^17y[1]^17 + 43x[1]^16y[1]^16 - 17x[1]^15y[1]^15 -
27x[1]^14y[1]^14 - 5x[1]^13y[1]^13 - 49x[1]^12y[1]^12 - 39x[1]^11y[1]^11 - 25x[1]^10y[1]^10 - 40x[1]^9y[1]^9 + 46x[1]^8y[1]^8 -
35x[1]^7y[1]^7 - 47x[1]^6y[1]^6 - 30x[1]^5y[1]^5 + 45x[1]^4y[1]^4 + 40x[1]^3y[1]^3 + 3x[1]^2y[1]^2 + 41x[1]y[1] + 26

-------------------------------
--this computation is too slow with Weyl.WeylMul(F,G)
```