Graphical plotting with Lua

Delbert Franz ddf at sonic.net
Sun Jan 16 16:43:19 EST 2011


> Hi,
> 
> I finally managed to make the Lua bindings of PLplot compile and work
> with OpenWrt.  All you need is to install those packages:
> 
>   plplot_5.9.7-3_xburst.ipk
>   plplot-linuxvga_5.9.7-3_xburst.ipk
>   plplot-lua_5.9.7-3_xburst.ipk
>   svgalib_1.4.3-1_xburst.ipk
> 
> From http://mosquito.dyndns.tv/~spock/openwrt/ 
> (probaly needs the 12-14 firmware)
> 
> A TGZ with the Lua examples for PLplot is also there:
> 
>   http://mosquito.dyndns.tv/~spock/openwrt/lua-plplot-examples.tgz
> 
> You should be able to run them via 'lua ./x01.lua' etc. from the
> nanonote's console.  Screenshots:
> 
>   http://mosquito.dyndns.tv/david/nanonote/lua-plplot-3d.png
>   http://mosquito.dyndns.tv/david/nanonote/lua-plplot.png
> 
> cheers,
> 
> David

So glad you got this working!  I have tried it on my machine and 
cannot sort out why I get the following message when I execute: 

lua ./x01.lua

Lua: error loading module 'plplotluac' from file '/usr/lib/lua/plplotluac.so':
            File not found

The require statement in plplot_examples_lua at line 11 is the source 
of this problem.  

Clearly the file '/usr/lib/lua/plotluac.so' is there.  It also shows 
up in the ld.so.cache list.  Apparently Lua cannot find something 
inside the named file--I'm guessing this is what the message means.  

Warning: Rant about obscure or confusing error messages from system 
software in Linux is ahead:)
---------------------------------------------------------------------

One problem with many error messages from Linux software is that you 
have to be a guru to understand what they mean.  This message is an 
example: 

1.  It says it is trying to load a module and cannot find it in 
'/usr/lib/lua/plotluac.so.' 

2.  Then why does the rest of message say: 'File not found'?  To me 
this implies that the only file mentioned in the message, 
'/usr/lib/lua/plplotluac.so', could not be found.  

3.  However, that seems to be patent nonsense because the file in 
question is there and furthermore the file appears in the ld.so.cache.  

4.  Should the message have said: "Module not found"?  Without knowing 
what is put into a dynamic library, I thought modules, but perhaps 
they are also files within files in some contexts?  
------------------------------------------------------------------- 

David, maybe you can help out on what is missing.  If the file is 
missing, maybe there is some "invisible" character in the name at some 
point.  Otherwise, perhaps there is really a module missing.  Or 
perhaps I have a prerequisite package that is not installed and was 
not detected by opkg?  

I double checked and I did download and install the packages listed. But
there could be something you have on your system that I do not have. 
Is there a way to check what version of firmware exists on the Nanonote?
Looking at the dates for some files in my toolchain, I see dates in 
early December.  I used the firmware package from one of my early compiles
for what I installed.  The dates are 9 and 10 December on some of the 
directories and some files I did not touch, such as LICENSE.
 

Thanks again for all your work.  Looking forward to doing good looking 
plots from Lua.  

              Delbert







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