Re: Assignment to a block inside a matrix
- To: mathgroup@smc.vnet.net
- Subject: [mg10660] Re: [mg10614] Assignment to a block inside a matrix
- From: jpk@max.mpae.gwdg.de
- Date: Fri, 30 Jan 1998 04:24:00 -0500
Hi,
it has nothing to do with Your function. You need a new Mathematica
kernel. You can download it from the FAQ page of WRI's web site.
Hope that helps
jens
> Hello,
> I have a package that works with the "symplectic unit matrix"
> defined for an n-degree of freedom Hamiltonian system by
>
> symJ[n_Integer]:=
> Block[{s},s=Table[0,{2n},{2n}];
> Do[
> s[[{k+1,k+2},{k+1,k+2}]]={{0,1},{-1,0}},
> {k,0,2n-2,2}
> ];s]
>
> I.e. the definition involves the assignment to a 2 by 2 sub-matrix. Can
> someone tell me authoritatively whether this programming construct is
> correct or whether I need to rewrite the function using ReplacePart or
> something? The reason I ask is as follows:
>
> This used to work just fine on both Windows 95 and Unix versions of
> Mathematica. It still works on Unix (HP version X 3.0.0.0x) but there
> are problems
> in the Windows95 version (it is 3.0.1.1x according to the Help/About
> Mathematica display and
> $Version evaluates to "Microsoft Windows 3.0 (April 25, 1997)").
>
> Specifically, I can calculate symJ[1], symJ[2] correctly but symJ[3]
> and symJ[4] cause the kernel crash. I get a message
>
> "This program has performed an illegal opearation and will be shut
> down. If the problem persists, contact the program vendor."
>
> Clicking on Details gives:
>
> MATHKERNEL caused an invalid page fault in module MATHDLL.DLL at
> 0137:0072d9ef. Registers:
> EAX=00000002 CS=0137 EIP=0072d9ef EFLGS=00010202 EBX=00a3e6b0 SS=013f
> ESP=01a3fad4 EBP=013bd998 ECX=00000001 DS=013f ESI=013661d4 FS=1907
> EDX=01309ba0 ES=013f EDI=00000000 GS=0000 Bytes at CS:EIP:
> 66 8b 47 02 24 07 3c 01 75 35 a1 e4 84 a0 00 8b Stack dump:
> 01396ee8 01396848 01365fcc 0131c484 00000006 00000002 00a3e6b0 0043edb4
> 00000018 0072dae3 013661d4 013bd898 00000002 00000000 013a14dc 0130b8d0
>
>
> I have checked that this does not happen with Windows version 3.0.0.0
> which is still installed here. I have also checked that both versions
> behave the same way on two different PCs with different hardware.
>
> If my function is properly defined then this would appear to be a bug
> introduced in Version 3.0.1.1x. If my function is not properly defined
> (and I was just lucky that it worked in the earlier version) then I
> would still expect something better than a kernel crash.
>
> John Jowett
>
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