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D.4.6.1 decompopts

Procedure from library decomp.lib (see decomp_lib).

Usage:
decompopts(); or decompopts("reset");

Return:
nothing

Note:
in the first case, it shows the setting of the control parameters;
in the second case, it kills the user-defined control parameters and
resets to the default setting which will then be displayed.

int DECMETH; Method for computing the univariate decomposition
0 : (default) Kozen-Landau
1 : von zur Gathen

int IMPROVE Choice of coefficients for the decomposition
$(g_1,\ldots,g_l,h)$ of a non-monic polynomials f.
0 : leadcoef( $g_1$) = leadcoef( $f$) and $g_2,\ldots,g_l,h$ are monic
1 : (default), content( $g_i$) = 1

int MINS
$f=g\circ h, (g_1,\ldots,g_m,h)$ of a non-monic polynomials f.
0 : g(0) = f(0), h(0) = 0 [ueberlegen fuer complete]
1 : (default), g(0)=0, h(0) = f(0)
2 : Tschirnhaus

int DECORD; The order in which the decomposition will be computed
0 : minfirst
1 : (default) maxfirst

int DEGONE; decompose also polynomials built on linear ones
0 : (default)
1 :

Example:
 
LIB "decomp.lib";
decompopts();
==> 
==>   === Global variables for decomp.lib === 
==> 
==>  -- DECMETH (int) not defined, implicitly 1
==>  -- MINS (int) not defined, implicitly 0
==>  -- IMPROVE (int) not defined, implicitly 1