5.1.89 option

Syntax:

option ()

Type:

string

Purpose:

lists all defined options.

Syntax:

option ( option_name )

Type:

none

Purpose:

sets an option.

Note:

To disable an option, use the prefix no.

Syntax:

option ( get )

Type:

intvec

Purpose:

dumps the state of all options to an intvec.

Syntax:

option ( set, intvec_expression )

Type:

none

Purpose:

restores the state of all options from an intvec (produced by option(get)).

Values:

The following options are used to manipulate the behavior of computations and act like boolean switches. Use the prefix no to disable an option. Notice that some options are ring dependent and reset to their default values on a change of the current basering.

none

turns off all options (including the prompt option).

returnSB

the functions syz, intersect, quotient, modulo return a standard base instead of a generating set if returnSB is set. This option should not be used for lift.

fastHC

tries to the find the highest corner of the staircase (HC) as fast as possible during a standard basis computation (only used for local orderings).

intStrategy

avoids division of coefficients during standard basis computations. This option is ring dependent. By default, it is set for rings with characteristic 0 and not set for all other rings.

oldStd

uses a more lazy approach in std computations, which was used in Singular version before 2-0 (and which may lead to faster or slower computations, depending on the example)

minRes

special (additional) minimizing during computations (res, mres),
assumes homogeneous case and degree-compatible ordering.

notRegularity

disables the regularity bound for res and mres (see regularity).

notSugar

disables the sugar strategy during standard basis computation.

notBuckets

disables the bucket representation of polynomials during standard basis computations. This option usually decreases the memory usage but increases the computation time. It should only be set for memory-critical standard basis computations.

prot

shows protocol information indicating the progress during the following computations: facstd, fglm, groebner, lres, mres, minres, mstd, res, sres, std, stdfglm, stdhilb, syz. See below for more details.

redSB

computes a reduced standard basis in any standard basis computation.

redTail

reduction of the tails of polynomials during standard basis computations. This option is ring dependent. By default, it is set for rings with global degree orderings and not set for all other rings.

redThrough

for inhomogeneous input, polynomial reductions during standard basis computations are never postponed, but always finished through. This option is ring dependent. By default, it is set for rings with global degree orderings and not set for all other rings.

sugarCrit

uses criteria similar to the homogeneous case to keep more useless pairs.

weightM

automatically computes suitable weights for the weighted ecart and the weighted sugar method.

The following options, which also control computations, are special, since they are not manipulated by the option command but by a direct assignment of a value. Reset the option by assigning the value 0; the command option(none) will not reset them! If there is a non-zero value assigned, the command option() prints the option.

multBound

a multiplicity bound is set (see multBound).

degBound

a degree bound is set (see degBound).

The last set of options controls the output of SINGULAR:

Imap

shows the mapping of variables with the fetch and imap commands.

loadLib

shows loading of libraries (set by default).

debugLib

warns about syntax errors during loading of libraries.

loadProc

shows loading of procedures from libraries.

mem

shows memory usage in square brackets (see memory).

prompt

shows prompt (>, resp. .) if ready for input (default).

reading

shows the number of characters read from a file.

redefine

warns about variable redefinitions (set by default).

usage

shows correct usage in error messages (set by default).

Example:

option(prot); option(); → //options: prot redefine usage prompt option(notSugar); option(); → //options: prot notSugar redefine usage prompt option(noprot); option(); → //options: notSugar redefine usage prompt option(none); option(); → //options: none ring r=0,x,dp; degBound=22; option(); → //options: degBound redTail redThrough intStrategy intvec i=option(get); option(none); option(set,i); option(); → //options: degBound redTail redThrough intStrategy

The output reported on option(prot) has the following meaning:

See degBound; multBound; std.