Problems installing xTensor

[Christian]

I have tried to install the xTensor package on my work computer and my
own laptop and it failed in both cases, though at different points.

1) My work desktop is running Mathematica v6 for Windows. I placed the
xAct package as instructed in:
C:\Program Files\Wolfram Research\Mathematica\7.0\AddOns\Applications\

Starting a notebook I can then load the xTensor package and seem to be
able to use it fine. (I used $PrePrint = ScreenDollarIndices; as it
initially showed dummy indices with $signs).
However the Spinors package can not be loaded, and I get:
In[1]:= Get::noopen: Cannot open xAct`Spinors`. \
>>
Out[1]= $Failed


2) My laptop runs on Vista with Mathematica 7. I placed the xAct
packkage in the same location.

Running <<xAct`xTensor` , I get asked for a mathlink for the xPerm
package. xPerm.win (as well as cygwin1.dll) are located in the
mathlink folder of xPerm. However the windows that opens to load only
looks for .exe files and does not show the above named files. It is
not possible to select All files as a display option.



I had a look in both (desktop and laptop) Documentation centers, the
add-ons list xAct and its substructures (in one it is displayed three
times, in the other it is twice) Do I need to remove some? On e of my
steps had been to try placing the xAct folder in one of the other
suggested locations - to no avail. I deleted all teh other ones apart
from teh one mentioned above again later.

I will try a few more things in the mean time.

Christian

[magma]

In MMA version 6 and 7,
I would suggest you place the xAct folder (containing all the xAct
component files)
into the folder displayed by the MMA command

$BaseDirectory

if you are the sole user of your machine.

It is typically something like:

C : \Documents and settings\All Users\Application \
data\Mathematica\Applications

if you are using a Windows English speaking system.

Or the one displayed by

$UserBaseDirectory

if you share the machine with someone else.

These 2 directory locations are the RECOMMENDED ones by WRI for
installing 3rd party add-ons.

The directory you are using was good in previous versions of MMA (<
6.0) and is NOT to be used any more.

By using $BaseDirectory or $UserBaseDirectory, MMA itself will tell
you where to put xAct.

Once you have xAct (and therefore xTensor) working properly, I would
suggest you to download and use xPrint, which is a friendly graphical
user interface to xAct.

You can read about xPrint in the prior posts in this group.
For example:
Introducing xPrint:
http://groups.google.com/group/xact/browse_thread/thread/40cdbad8c777e973

xPrint can be downloaded at:
http://sites.google.com/site/xprintforxact/

[Alfonso Garcia-Parrado]

Hi Christian,

> 1) My work desktop is running Mathematica v6 for Windows. I placed the
> xAct package as instructed in:
> C:\Program Files\Wolfram Research\Mathematica\7.0\AddOns\Applications\
>
> Starting a notebook I can then load the xTensor package and seem to be
> able to use it fine. (I used $PrePrint = ScreenDollarIndices; as it
> initially showed dummy indices with $signs).
> However the Spinors package can not be loaded, and I get:
> In[1]:= Get::noopen: Cannot open xAct`Spinors`. \
> >>
> Out[1]= $Failed
>

Which instruction did you issue when you tried to load "Spinors" ?
Also, I don't understand why you have a path named
"C:\..\7.0\..\Applications\" in a Mathematica 6 installation. Shouldn't
the number be 6.0 ? Are you able to load "Spinors" when working with
Mathematica 7 or after following the indications pointed out in the
previous message of this list?

Regards,

Alfonso.

[Christian]

Hi Magma and Alfonso,

Thank you for your comments.

Quick clarification: the path I gave was copied straight from the
installation notes. The path on the desktop is indeed ...\6.0\... for
version 6. Sorry Alfonso for the confusion this caused.

However progress has been made in the mean time. In short Spinors
works on both machines

In more detail:

Following Magma's comments for my laptop, I used
$BaseDirectory
to find C:\ProgramData\Mathematica
Once I placed the xAct-package in the 'Applications' folder found in
the indidcated location (and deleted all the previous ones), I was
able to run xTensor on my laptop. Note the problem with the dummy
indicies occured here as well.

For the spinor package I have been using the command
<<xAct`Spinors`
This still gives the error message indicated in my initial email.

For the desktop:
I copied the original downloaded version into the path given to me by
$UserBaseDirectory
and still faced the old problem of loading the spinor package, while
xTensor continued to work. [Note at this stage admin rights prevent me
from deleting the package in the other locations on the system]

The problem was solved when I replaced the xAct folder unpacked from
the web-download with the xAct folder that Thomas Backdahl is
successfully using on his laptop.
His version of xAct`Spinors` is 0.9.2, {2009,9 ,9}, but does contain
some modified files that have been individually updated.
I can now use the spinor package successfully on both computers. The
problem with the dummy indices doesn't occur either.

So at my end everything works for now. But the question remains
whether I used the wrong command for the Spinors package or where my
problems with the downloaded package originated from.

Christian

[magma]

> Quick clarification: the path I gave was copied straight from the
> installation notes. The path on the desktop is indeed ...\6.0\... for
> version 6. Sorry Alfonso for the confusion this caused.

I know, the installation notes should perhaps emphasize that different
folders should be used with different versions of MMA.

It appears that neither I can load Spinors.
So it seems a general problem with the package (or the current
location of the package).

[Alfonso Garcia-Parrado]

Hi Christian,

thanks for your explanations.

> So at my end everything works for now. But the question remains
> whether I used the wrong command for the Spinors package or where my
> problems with the downloaded package originated from.
>

I am happy that you found a work-around and that you can already work
with "Spinors". The command you used to load spinors is the right one
and it seems to me that the problem loading spinors only
happens in a Windows environment (I am a Linux user and I never tested
Spinors under Windows). I am going to perform tests under Windows and
try to figure out what is wrong. Then I will post in this list an answer
to this problem.

Regards,

Alfonso.

[JMM]

Hi,

On Jun 14, 11:58 pm, magma <mader...@gmail.com> wrote:
> > Quick clarification: the path I gave was copied straight from the
> > installation notes. The path on the desktop is indeed ...\6.0\... for
> > version 6. Sorry Alfonso for the confusion this caused.
>
> I know, the installation notes should perhaps emphasize that different
> folders should be used with different versions of MMA.

As you said before, if we use only the $BaseDirectory and
$UserBaseDirectory the problem disappears because those two are
version-independent. Hence for the next release I will change the
recommendations of the install file following your suggestions in your
previous email.

> It appears that neither I can load Spinors.
> So it seems a general problem with the package (or the current
> location of the package).

Indeed, I have found that I forgot to add the file xAct/Spinors.m in
the windows distribution, which is the file you load when writing
xAct`Spinors` . This must be a copy of xAct/Spinors/Spinors.m or a
link to it. Thanks Christian and Alessandro for reporting this.

Cheers,
Jose.

[Jose]

Hi Bob,

xAct` is not a package, but a collection of packages. You always need
to load one of the packages, say

Needs["xAct`xTensor`"]

but Needs["xAct`"] is not going to work.

If this doesn't solve your problem, then tell us where exactly you
have put the xAct directory, and whether it is one of the directories
listed in $Path.

Cheers,
Jose.

On Oct 10, 4:51 pm, Bob Korsan <bobkor...@gmail.com> wrote:
> Hi I am using MMA Home Edition 8.x under Lion. I am trying to install xAct
> with xTensor, xPrint, etc in the main folder. I have put it in various
> places including an alias in $UserBaseDirectory. Every time I try a Needs,
> I get
>
> Needs["xAct`"]
>
> Get::noopen: Cannot open xAct`. >>
>
> Needs::nocont: Context xAct` was not created when Needs was evaluated. >>
>
> $Failed
>
> and this was because I was trying to read the xPrint documentation and got
> the same when I tried Needs["xAct`xPrint`].
>
> HELP?????
>
> Cheers/Bob

[Jose]

We first need to know whether you have a problem with the installation
of xAct or with the (separate) installation of xPrint. So try lo load
xAct`xTensor` and tell me whether that works.

You don't have to install xAct in several directories. In fact it is a
bad idea because you will get confused about which one must be
patched, if you need it. For example, to make it available to all your
users, have the directory /Library/Mathematica/Applications/xAct/ with
all packages inside it. Remove all other installations of xAct. Then
do Needs["xAct`xTensor`"], as I write it, and see whether this works
or else gives you ::noopen messages.

You can also execute

FindFile["xAct`xTensor`"]

to see where (or if) Mathematica finds that file in your $Path.

Jose.

On Oct 11, 6:55 pm, Bob Korsan <bobkor...@gmail.com> wrote:
> Hi, I tried Needs["xAct"] because Needs["xAct`xPrint`"] didn't work. That
> was my original problem.
>
> I put xPrint inside the xAct folder (with a link to xPrint.m inside the
> xAct folder just like all the other packages in the folder) and put the
> xAct folder in several places:
>
> $UserBaseDirectory,
> MacintoschHD/Applications/Mathematica\ Home\ Edition.app/Addons/Applications
> /Library/Mathematica/Applications
> /Users/admin/Library/Mathematica/Applications
>
> (BTW I'm admin on my machine)
>
> It didn't work in any of these places. I also put it in one with links to
> the xAct folder in the others. Still didn't work.
> That is why I finally posted here. I'm stumped.

>
>
>
>
>
>
>
> On Wednesday, October 10, 2012 8:53:15 PM UTC-7, Jose wrote:
>
> > Hi Bob,
>
> > xAct` is not a package, but a collection of packages. You always need
> > to load one of the packages, say
>
> > Needs["xAct`xTensor`"]
>
> > but Needs["xAct`"] is not going to work.
>
> > If this doesn't solve your problem, then tell us where exactly you
> > have put the xAct directory, and whether it is one of the directories
> > listed in $Path.
>
> > Cheers,
> > Jose.
>
> > On Oct 10, 4:51 pm, Bob Korsan <bobkor...@gmail.com> wrote:
> > > Hi I am using MMA Home Edition 8.x under Lion. I am trying to install
> > xAct
> > > with xTensor, xPrint, etc in the main folder. I have put it in various

> > .................

[Jose]

> OK! Needs["xAct`xTensor`"] works and FindFile shows the proper directory.

Great.

> So, I have an xAct sub-folder xPrint111 with xPrint.m in it. I have a link
> to xPrint.m at the top level of xAct. Needs["xAct`xPrint`"] (executed from
> the notebook xPrint Documentation.nb) still gives a No Open message. At
> least we know it is not folder placement, I must have screwed up something
> in the way I put xPrint in the xAct folder.

Perhaps Alessandro should confirm this, but I think xPrint is designed
so that

1) xPrint.m is in the main directory xAct/ . There is no need to have
a xAct/xPrint/ subdirectory.

2) The documentation file xPrintDoc.nb should be in xAct/Documentation/
English/

> I have xPrint.m in the Documentation subfolder of the xPrint111 folder (at the top level of the
> xAct folder).

That seems wrong.

> Any thoughts? Repeating myself, there is a xPrint.m link
> (alias) at the top level of xAct (folder).

I would recommend to put the real file there, and not a link. It is
simpler.

Cheers,
Jose.

[Teake Nutma]

Hi,

I just installed xPrint by putting xPrint.m in the main xAct directory (no symlinks or subfolders, like Jose said), and that seems to work.
Best,

Teake

> --