# Difference between revisions of "ApCoCoA-1:Weyl.WMulByMonom"

## Weyl.WMulByMonom

Computes the product M*F of a Weyl monomial M and a Weyl polynomial F in normal form.

### Syntax

```Weyl.WMulByMonom(M:POLY,F:POLY):POLY
```

### Description

This function multiplies a Weyl monomial M with a polynomial F and returns M*F as a Weyl polynomial in normal form.

• @param M A Weyl monomial.

• @param F A Weyl polynomial.

• @return The product M*F, a Weyl polynomial in normal form.

Note: Monomials and polynomials that are not in normal form should be first converted into normal form using Weyl.WNormalForm, otherwise you may get unexpected results.

#### Example

```A1::=QQ[x,d];	--Define appropriate ring
Use A1;
M:=x^3d^4; F:=x^3+d^3+3xd+5;
Weyl.WMulByMonom(M,F);
x^6d^4 + x^3d^7 + 3x^4d^5 + 12x^5d^3 + 17x^3d^4 + 36x^4d^2 + 24x^3d
-------------------------------
Weyl.WMulByMonom(F,M); -- note the input
ERROR: 1st parameter should be a Monomial!
CONTEXT: Error(<quotes>1st parameter should be a Monomial!</quotes>)
-------------------------------
```