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:
  facstd F found a new factor
    all other characters: like the output of std and reduce
  fglm . basis monomial found
   + edge monomial found
   - border monomial found
  groebner  all characters: like the output of std
  lres . minimal syzygy found
   n slanted degree, i.e., row of Betti matrix
   (mn) calculate in module n
   g pair found giving reductum and syzygy
  mres [d] computations of the d-th syzygy module
    all other characters: like the output of std
  minres [d] minimizing of the d-th syzygy module
  mstd  all characters: like the output of std
  reduce r reduced a leading term
   t reduced a non-leading term
  res [d] computations of the d-th syzygy module
    all other characters: like the output of std
  sres . syzygy found
   (n) n elements remaining
   [n] finished module n
  std [m:n] internal ring change to poly representation with exponent bound
m and n words in exponent vector
   s found a new element of the standard basis
   - reduced a pair/S-polynomial to 0
   . postponed a reduction of a pair/S-polynomial
   h used Hilbert series criterion
   H(d) found a 'highest corner' of degree d, no need to consider higher degrees
   (n) n critical pairs are still to be reduced
   (S:n) doing complete reduction of n elements
   d the degree of the leading terms is currently d
  stdfglm  all characters in first part: like the output of std
    all characters in second part: like the output of fglm
  stdhilb  all characters: like the output of std
  syz  all characters: like the output of std


See
degBound;
multBound;
std.
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&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; User manual for <a href="http://www.singular.uni-kl.de/"><i>Singular</i></a> version 2-0-4, October 2002,
generated by <a href="http://www.gnu.org/software/texinfo/"><i>texi2html</i></a>.
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