Top
Back: symmStd
Forward: derham_lib
FastBack: realizationMatroids_lib
FastForward: derham_lib
Up: symodstd_lib
Top: Singular Manual
Contents: Table of Contents
Index: Index
About: About this document

D.15.19.6 syModStd

Procedure from library symodstd.lib (see symodstd_lib).

Usage:
syModStd(I,sigma); I ideal, sigma intvec

Assume:
size(sigma) = nvars(basering) and sigma(I) = I. If size(#) > 0, then # contains either 1, 2 or 4 integers such that
- #[1] is the number of available processors for the computation,
- #[2] is an optional parameter for the exactness of the computation, if #[2] = 1, the procedure computes a standard basis for sure,
- #[3] is the number of primes until the first lifting,
- #[4] is the constant number of primes between two liftings until the computation stops.

Return:
ideal, a standard basis of I if no warning appears;

Note:
The procedure computes a standard basis of the ideal I (over the rational numbers) by using modular methods and the fact that I is invariant under the variable permutation sigma.
By default the procedure computes a standard basis of I for sure, but if the optional parameter #[2] = 0, it computes a standard basis of I with high probability.
The procedure distinguishes between different variants for the standard basis computation in positive characteristic depending on the ordering of the basering, the parameter #[2] and if the ideal I is homogeneous.
- variant = 1, if I is homogeneous,
- variant = 2, if I is not homogeneous, 1-block-ordering,
- variant = 3, if I is not homogeneous, complicated ordering (lp or > 1 block),
- variant = 4, if I is not homogeneous, ordering lp, dim(I) = 0.

Example:
 


Top Back: symmStd Forward: derham_lib FastBack: realizationMatroids_lib FastForward: derham_lib Up: symodstd_lib Top: Singular Manual Contents: Table of Contents Index: Index About: About this document
            User manual for Singular version 3-1-6, Dec 2012, generated by texi2html.