Transforming a polynomial in internal format into a list and back

11.1.6 Transforming a polynomial in internal format into a list and back

The convert command does many conversions (see Section 10.1.10). Among other things, it can convert between a polynomial in internal sparse multivariate format and a list representing the polynomial.

To convert from a polynomial in internal sparse multivariate format to a list, convert takes one mandatory argument and one optional argument:
- P, a polynomial written in internal sparse multivariate format (see Section 11.1.2).
- Optionally, list.
convert(P ⟨, list⟩) returns a list representing the polynomial.
To convert from a list representing a polynomial to the polynomial in internal sparse multivariate formatconvert takes two arguments:
- L, a list representing a polynomial.
- polynom.
convert(L,polynom) returns the polynomial in internal sparse multivariate format (see Section 11.1.2).

Examples

p:=symb2poly(x^2-x*y+2y,[x,y])

%%%{1,[2,0]%%%}+%%%{−1,[1,1]%%%}+%%%{2,[0,1]%%%}

l:=convert(p,list)

or:

l:=convert(p)

⎡
⎢
⎢
⎢
⎢
⎢
⎣

⎡
⎣

2,0

⎤
⎦

−1

⎡
⎣

1,1

⎤
⎦

⎡
⎣

0,1

⎤
⎦

⎤
⎥
⎥
⎥
⎥
⎥
⎦

which is a list of the coefficients followed by a list of the variable powers.

convert(l,polynom)

%%%{1,[2,0]%%%}+%%%{−1,[1,1]%%%}+%%%{2,[0,1]%%%}