|
D.15.19.5 symmStd
Procedure from library symodstd.lib (see symodstd_lib).
- Usage:
- symmStd(I,sigma,#); I ideal, sigma intvec
- Assume:
- size(sigma) = nvars(basering) =: n, basering has an order(sigma)-th
primitive root of unity a (if char(basering) > 0) and sigma(I) = I
- Return:
- ideal, a standard basis of I
- Note:
- Assuming that the ideal I is invariant under the variable permutation
sigma and the basering has an order(sigma)-th primitive root of unity
the procedure uses linear transformation of variables in order to
improve standard basis computation.
If char(basering) = 0 all computations are done in the polynomial ring
over the smallest field extension that has an order(sigma)-th primitive
root of unity.
Example:
|