> < ^ Date: Mon, 09 Oct 2000 13:54:05 +0200 (MESZ)
^ From: Michael Weller <eowmob@exp-math.uni-essen.de >
> ^ Subject: Compressed vectors/matrices are always 0.

Dear List,

I need to do some finite field matrix computations over GF(43) of high
enough dimensions s.t. the compressed storage technique is absolutely
needed. Alas, whenever I ConvertToMatrixRep or even ConvertToVectorRep
I end up with a zero matrix/vector. This is the case for all machines and
fields I tried. Even for GF(2) like in the example below:

         #########      #####          #####  #####                ####  

Information at: http://www-gap.dcs.st-and.ac.uk/~gap
? for help. Copyright and authors list by ?copyright, ?authors

   Loading the library. Please be patient, this may take a while.
GAP4, Version: 4r2 fix2 of 7-April-2000, rs6000-ibm-aix4.2.1.0-gcc
Components:  small, small2, small3, small4, small5, small6, small7, 
             small8, id2, id3, id4, id5, id6, trans, prim, tbl, 
             tom  installed.
gap> test := [1,0,1,0,1];
[ 1, 0, 1, 0, 1 ]
gap> MakeImmutable(test);
gap> ConvertToVectorRep(test, 2);
gap> test;
<an immutable GF2 vector of length 5>
gap> Print(test);
[ 0*Z(2), 0*Z(2), 0*Z(2), 0*Z(2), 0*Z(2) ]gap> 

Of course, the matrix/vector is not just printed as 0 it also seems to
behave like zero.

This is the same for compilations by i686-pc-linux-gnu-gcc and
alphaev6-unknown-linux-gnu-gcc on the resp. hardware (where the latter is
the most if not the only one interesting to me), s.t. a specific problem
with a certain machine word size or byte ordering seems not to be the

Is this a known problem (and fixed by one of the recent patches) or am I
just doing something wrong?

Please advise! Thanks in advance,
M. Weller.


Michael Weller: eowmob@exp-math.uni-essen.de, eowmob@ms.exp-math.uni-essen.de,
or even mat42b@spi.power.uni-essen.de. If you encounter an eowmob account on
any machine in the net, it's very likely it's me.

Miles-Receive-Header: reply

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