> < ^ From:

< ^ Subject:

Dear Mrs. and Mr. Forum,

Gary Schwartz writes in his message of today:

I am having a problem creating libraries of character tables. I'm

running GAP 3.2 on a 486 PC. It seems that in the last paragraph of

section 46.6 of the manual, you say that the file which is printed by

PrintToLib must be edited, but there's no example and I don't

understand. Please give me an example starting with an arbitrary

character table that you want to save, and please include all the steps

from saving it, to notififying the library table, to reading it back.

Here is an example. Just now I realized that it might be not very

comfortable to include character tables in a private library. In the

next version this will be a bit easier.

Let's say we are interested in the table of the symmetric group S3 ...

gap> CharTable( "S3" );;

#E CharTableLibrary: no library table with name 'S3'

.. but it is not in the library. So let's add it.

gap> g:= SolvableGroup( 6, 2 ); S3 gap> t:= CharTable( g );; gap> t.name; "S3" gap> PrintToLib( "table", t );

The file 'table' in the current directory contains the table.

We have to notify it, and want to allow access to it as 'mytable'.

(This must be done for every GAP session, for example statements like

this can be put into the '.gaprc' file.)

NotifyCharTable( t.name, "table", [ "mytable" ] );

Now there are two problems. The first is that GAP does not know

in which directories it shall search for the tables; therefore we

add the pathname of the directory to 'TBLNAME'.

gap> TBLNAME; "/usd/gap/3.3/tbl/" gap> Append( TBLNAME, ";/usd/sam/tbl/" );

The second problem (or a bug in GAP, perhaps) is that table files

are expected to have an extension '.tbl', but our file has not yet.

(This will be fixed in the next version of GAP.)

gap> Exec( "mv table table.tbl" );

Now we are done.

gap> new:= CharTable( "mytable" );;

gap> DisplayCharTable( new );

S32 1 . 1 3 1 1 .1a 3a 2a 2P 1a 3a 1a 3P 1a 1a 2aX.1 1 1 1 X.2 1 1 -1 X.3 2 -1 .

Note that at the moment it might cause difficulties if the filename

contains special characters, e.g. '.'; this will also be fixed in the

next version of GAP.

Kind regards

Thomas Breuer

(sam@ernie.math.rwth-aachen.de)

> < [top]