SaveDecompositionMatrix(d)
SaveDecompositionMatrix(d, filename)
The function SaveDecompositionMatrix
saves the decomposition matrix
d. After a decomposition matrix has been saved, the functions
H.S
, H.P
, and H.D
will automatically access it as needed. So,
for example, before saving d in order to retrieve the indecomposable
P
(mu) from d it is necessary to type H.P(d, mu)
;
once d has been saved, the command H.P(mu)
suffices.
Since InducedDecompositionMatrix(d)
consults the decomposition
matrices for smaller n, if they are available, it is advantageous to
save decomposition matrices as they are calculated. For example, over
a field of characteristic~5, the decomposition matrices for the
symmetric groups Sym_n with n le 20 can be calculated as
follows:
gap> H:=Specht(5,5);; gap> d:=DecompositionMatrix(H,9);; gap> for r in [10..20] do > d:=InducedDecompositionMatrix(d); > SaveDecompositionMatrix(d); > od;
If your Hecke algebra record H
is defined using a non--standard
valuation map (see Specht) then it is also necessary to set the
string ``H.HeckeRing
'', or to supply the function with a
filename before it will save your matrix. SaveDecompositionMatrix
will also save adjustment matrices and the various other matrices that
appear in Specht (they can be read back in using
DecompositionMatrix
). Each matrix has a default filename which you
can over ride by supplying a filename. Using non--standard file
names will stop Specht from automatically accessing these matrices
in future.
See also DecompositionMatrix DecompositionMatrix
DecompositionMatrix and CrystalDecompositionMatrix
CrystalDecompositionMatrix. This function requires the package
``specht'' (see RequirePackage).
GAP 3.4.4