 Rank: Newbie
Groups: Registered
Joined: 06/02/2010(UTC)
Posts: 8
Location: uk
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hi
i was trying to invert a matrix with smath winxp 2010-feb10 version.
It gives me an error that "matrix is noninvertible (determinant equals zero)".
the determinant is not zero, i have checked. i have tried the M^-1 and invert(M) too. but gives the same error.
if i do this, then it works, calculates the result:
M:=...
M^-1= RESULT
if I do this, then it does not work:
M:=...
M2:=M^-1
M2= ERROR
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Rank: Newbie
Groups: Registered
Joined: 06/02/2010(UTC)
Posts: 8
Location: uk
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M=1/sqrt(2)*mat(1,-1,0,0,0,0,1,-1,1,1,0,0,0,0,1,1,4,4)
det(M)=-1 so it is not zero
if i change the matrix, to get a different determinant, not -1, then it wors.
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  Rank: Administration Groups: Developers, Registered, Knovel Developers, Administrators, Advanced Member Joined: 11/07/2008(UTC) Posts: 1,616   Was thanked: 1978 time(s) in 666 post(s)
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Hello. I can't reproduce this error with my matrices:  Could you please send your full example to support[at]smath[dot].info? Best regards, Andrey Ivashov.
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Rank: Administration Groups: Developers, Registered, Knovel Developers, Administrators, Advanced Member Joined: 11/07/2008(UTC) Posts: 1,616 Was thanked: 1978 time(s) in 666 post(s)
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OK, I see now, thanks. Will check in 5 hrs.
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Rank: Administration Groups: Developers, Registered, Knovel Developers, Administrators, Advanced Member Joined: 11/07/2008(UTC) Posts: 1,616 Was thanked: 1978 time(s) in 666 post(s)
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Figured out that this error was in previous versions of SMath Studio as well when trying to evaluate symbolically:
(1/sqrt(2)*mat(1;-1;0;0;0;0;1;-1;1;1;0;0;0;0;1;1;4;4))^{-1}—#
Starting work to fix it.
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Rank: Newbie
Groups: Registered
Joined: 06/02/2010(UTC)
Posts: 8
Location: uk
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Rank: Administration Groups: Developers, Registered, Knovel Developers, Administrators, Advanced Member Joined: 11/07/2008(UTC) Posts: 1,616 Was thanked: 1978 time(s) in 666 post(s)
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Here is modified version of SyLib.dll file for SMath Studio 0.87 where this bug fixed: http://smath.info/?file=739022 (just unpack it and replace original SyLib.dll from Program Files/SMath/SMath Studio folder). You can use it till next version of the program will be released. Regards. Edited by user 15 February 2010 07:20:05(UTC)
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