Cygwin Problems in Win 8.1

[Jonathan]

Hi all,

I just put xAct on a fresh install of Windows 8.1 and am getting an error in the linked DOS terminal from cygwin:

0 [main] xperm.win 3360 find_fast_cwd: WARNING: Couldn't compute FAST_CWD pointer.

From searching around, it seems that this problem is caused by using an older version of cygwin. The only solution I can think of is to replace cygwin1.dll in the mathlink folder, though I'm a little hesitant to do this. The package still seems to work but certain computations take longer to finish (e.g. 145 s instead of 80 s). Any ideas for a fix?

Thanks,
Jonathan

[Hidetomo Yanase]

I got same error ! Windows8.1 64bit. I can not install help me!

2013年12月7日土曜日 15時29分20秒 UTC+9 Jonathan:

[Thomas Bäckdahl]

Hi!

I don't have Windows 8, so I can not test this myself. (I have Windows 7 and refuse to install Windows 8).

According to the latest cygwin release information, the latest version of cygwin has a workaround for some kind of bug in Windows 8.
I don't know if this is related to your problem, but it might be.
Hence, I tested the new cygwin1.dll with the current xperm.win. Unfortunately that failed. I suppose that we need version of xperm.win compiled under the latest cygwin.
I have spent a few hours trying to compile xperm under cygwin but failed. I even get syntax errors in mathlink.h so I am obviously doing something wrong.
Can anyone compile it? Both a 32 bit and a 64 bit version would be nice. If you succeed, please tell me how to do it.

A temporary fix is to not use the external xperm.win at all.
One way to do this is to change
$xpermQ=xpermConnect;
to
$xpermQ=False;
in xPerm.m

This will let you do all calculations, but only the much slower mathematica implementation of the canonicalizer will be used.

Regards
Thomas

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[Thomas Bäckdahl]

Hi!

I managed to recompile xperm.win with a 64 bit version of MinGW.
It seems to work under a 64 bit Windows 7, but I have not been able to
test it with Windows 8.
This is no longer cygwin so there is no DOS like terminal window any
longer. For me the runtimes seems to be similar to the old cygwin
version. Perhaps some optimization parameters can be set for the compiler.

Please report any success or fail with this version.

Regards
Thomas

[Jonathan]

That seems to have stopped the error post, though I don't know if it has entirely fixed things. Computations take the same amount of time running with xperm now as they do using the mathematica canonicalizer by setting xpermQ=False.

Thanks for the help!

[Thomas Bäckdahl]

Hi!

On 2014-01-24 20:47, Jonathan wrote:

That seems to have stopped the error post, though I don't know if it has entirely fixed things. Computations take the same amount of time running with xperm now as they do using the mathematica canonicalizer by setting xpermQ=False.

This is strange. What are the results if you evaluate $xpermExecutable and $xpermLink?

Regards
Thomas

[Kungi Dito]

Hi,

I have the same problem

 [main] startxwin 4036 find_fast_cwd: WARNING: Couldn't compute FAST_CWD pointer. 

Have googled for some time and it seems to me that the method for getting the FAST_CWD is broken in newest windows8.1

I have read in some cyg dev correspondence that they used some ugly hack to get it from some dll, and I guess that the

dll changed so now they have to update the method or something

Cheers

[Thomas Bäckdahl]

Hi!

I believe that this problem is fixed now. Download the latest version of xAct version 1.1.0. The xperm executable is recompiled and now uses MinGW instead of cygwin.
Please report if this does not help.

Regards
Thomas

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[Kungi Dito]

I'm afraid my problem is not directly related to using xAct and therefore the download wont fix anything (I don't even have mathematica on my pc)

My error came up when i was running startx11

I was hoping the fix was of a more general nature

Cheers