[Tex/LaTex] Strange problem with pgf/tikz auxlock file when invoking tikzexternalize

gnuplotluatextikz-external

I'm trying to generate a number of somewhat complicated TikZ based plots using gnuplot's lua/tikz terminal. Things had been working fine last month, but when I needed to update some of these plots today, things did not work. I've constructed a minimal example of a gnuplot script and a TeX file that produces the error.

The problem is, when I run lualatex --shell-escape --interaction=nonstopmode test.in I get, amidst the copious output, the following error:

===== 'mode=convert with system call': Invoking 'lualatex --halt-on-error --int
eraction=batchmode --jobname "TikZ_figs/fig1" "\def\tikzexternalrealjob{test}\i
nput{test}"' ========
This is LuaTeX, Version beta-0.50.0-2010010505
! I can't write on file `test.auxlockalt-on-error --interaction=batchmode --job
name "TikZ_figs/fig1" "\def\tikzexternalrealjob{test}\input{test}"'.
\tikzexternalauxlock@setlock ...@realjob .auxlock 
                                                  \immediate \write \w@pgf@w...
l.74 \end{tikzpicture}

Please type another output file name
! Emergency stop.

I'd like to keep the -interaction=nonstopmode flag, because I'd like to keep using TeXlipse to compile the document.
Removing this flag gives a prompt at

Please type another output file name:

If I enter the name test.auxlock (which seems to be the correct name, as the contents of this file contain only a single line: \def \tikzexternallocked {0}), then I get the same error (this time, just a warning) but without the emergency stop, thrown because of -interaction=nonstopmode.

The build then goes on and successfully generates the main document and the externalized graphics. If I leave the prompt blank, on the other hand, the test.auxlock file overwrites the main tex file test.tex. Quite distressing!

It seems that the invocation line for tikzexternalize is being used as the filename for the auxlock file. I don't know why this happens, or how to prevent it.

Is this something I'm experiencing because of some buggy installation? (As I said, it used to work and now it doesn't, I may have updated something or corrupted some file.)

I'm running texlive on Ubuntu 10.10, with pgf 2.10 from Ubuntu 12.04 (since pgf from Ubuntu 10.10 doesn't have the proper externalize routines) and texlive-luatex 2009-7.

Files and directories for minimal working example:

test.plt
test.tex
TikZ_files/

Code for MWE

Gnuplot script test.plt:

#!/usr/bin/gnuplot
#test.plt - create some plots to be rendered with TikZ

set term tikz
set output 'fig1.tex'
plot sin(x)/x

set output 'fig2.tex'
plot erf(x)

Main tex file test.tex:

%test.tex - MWE for lualatex auxlock file error
\documentclass[]{report}

\usepackage{tikz}
\usetikzlibrary{external}
\usepackage{gnuplot-lua-tikz}
\tikzset{ external/system call={lualatex \tikzexternalcheckshellescape
          --halt-on-error --interaction=batchmode
          --jobname "\image" "\texsource"} }
\tikzexternalize[
  mode=convert with system call,
  prefix=TikZ_figs/
]

\begin{document}

  \begin{figure}
    \tikzsetnextfilename{fig1}
    \input{fig1.tex}
    \caption{\label{fig:fig1} A plot of sinc($x$).}
  \end{figure}

  \begin{figure}
    \tikzsetnextfilename{fig2}
    \input{fig2.tex}
    \caption{\label{fig:fig2} A plot of erf($x$).}
  \end{figure}

\end{document}

If you don't have lua/tikz support compiled into gnuplot, the gnuplot script won't work, sorry about that.
The tex files generated by gnuplot (fig1.tex and fig2.tex) are longish, but here goes.

fig1.tex:

\begin{tikzpicture}[gnuplot]
%% generated with GNUPLOT 4.6p0 (Lua 5.1; terminal rev. 99, script rev. 100)
%% Tue 22 May 2012 10:34:12 PM EDT
\path (0.000,0.000) rectangle (12.500,8.750);
\gpcolor{color=gp lt color border}
\gpsetlinetype{gp lt border}
\gpsetlinewidth{1.00}
\draw[gp path] (1.196,0.616)--(1.376,0.616);
\draw[gp path] (11.947,0.616)--(11.767,0.616);
\node[gp node right] at (1.012,0.616) {-0.4};
\draw[gp path] (1.196,1.725)--(1.376,1.725);
\draw[gp path] (11.947,1.725)--(11.767,1.725);
\node[gp node right] at (1.012,1.725) {-0.2};
\draw[gp path] (1.196,2.835)--(1.376,2.835);
\draw[gp path] (11.947,2.835)--(11.767,2.835);
\node[gp node right] at (1.012,2.835) { 0};
\draw[gp path] (1.196,3.944)--(1.376,3.944);
\draw[gp path] (11.947,3.944)--(11.767,3.944);
\node[gp node right] at (1.012,3.944) { 0.2};
\draw[gp path] (1.196,5.053)--(1.376,5.053);
\draw[gp path] (11.947,5.053)--(11.767,5.053);
\node[gp node right] at (1.012,5.053) { 0.4};
\draw[gp path] (1.196,6.162)--(1.376,6.162);
\draw[gp path] (11.947,6.162)--(11.767,6.162);
\node[gp node right] at (1.012,6.162) { 0.6};
\draw[gp path] (1.196,7.272)--(1.376,7.272);
\draw[gp path] (11.947,7.272)--(11.767,7.272);
\node[gp node right] at (1.012,7.272) { 0.8};
\draw[gp path] (1.196,8.381)--(1.376,8.381);
\draw[gp path] (11.947,8.381)--(11.767,8.381);
\node[gp node right] at (1.012,8.381) { 1};
\draw[gp path] (1.196,0.616)--(1.196,0.796);
\draw[gp path] (1.196,8.381)--(1.196,8.201);
\node[gp node center] at (1.196,0.308) {-10};
\draw[gp path] (3.884,0.616)--(3.884,0.796);
\draw[gp path] (3.884,8.381)--(3.884,8.201);
\node[gp node center] at (3.884,0.308) {-5};
\draw[gp path] (6.572,0.616)--(6.572,0.796);
\draw[gp path] (6.572,8.381)--(6.572,8.201);
\node[gp node center] at (6.572,0.308) { 0};
\draw[gp path] (9.259,0.616)--(9.259,0.796);
\draw[gp path] (9.259,8.381)--(9.259,8.201);
\node[gp node center] at (9.259,0.308) { 5};
\draw[gp path] (11.947,0.616)--(11.947,0.796);
\draw[gp path] (11.947,8.381)--(11.947,8.201);
\node[gp node center] at (11.947,0.308) { 10};
\draw[gp path] (1.196,8.381)--(1.196,0.616)--(11.947,0.616)--(11.947,8.381)--cycle;
\node[gp node right] at (10.479,8.047) {sin(x)/x};
\gpcolor{color=gp lt color 0}
\gpsetlinetype{gp lt plot 0}
\draw[gp path] (10.663,8.047)--(11.579,8.047);
\draw[gp path] (1.196,2.533)--(1.305,2.628)--(1.413,2.736)--(1.522,2.853)--(1.630,2.974)%
  --(1.739,3.094)--(1.848,3.210)--(1.956,3.315)--(2.065,3.405)--(2.173,3.476)--(2.282,3.524)%
  --(2.391,3.546)--(2.499,3.539)--(2.608,3.502)--(2.716,3.435)--(2.825,3.339)--(2.934,3.216)%
  --(3.042,3.070)--(3.151,2.905)--(3.259,2.725)--(3.368,2.539)--(3.477,2.351)--(3.585,2.171)%
  --(3.694,2.004)--(3.802,1.860)--(3.911,1.745)--(4.019,1.667)--(4.128,1.631)--(4.237,1.644)%
  --(4.345,1.708)--(4.454,1.827)--(4.562,2.002)--(4.671,2.233)--(4.780,2.517)--(4.888,2.853)%
  --(4.997,3.234)--(5.105,3.653)--(5.214,4.104)--(5.323,4.577)--(5.431,5.063)--(5.540,5.551)%
  --(5.648,6.030)--(5.757,6.490)--(5.866,6.919)--(5.974,7.308)--(6.083,7.648)--(6.191,7.930)%
  --(6.300,8.148)--(6.409,8.297)--(6.517,8.372)--(6.626,8.372)--(6.734,8.297)--(6.843,8.148)%
  --(6.952,7.930)--(7.060,7.648)--(7.169,7.308)--(7.277,6.919)--(7.386,6.490)--(7.495,6.030)%
  --(7.603,5.551)--(7.712,5.063)--(7.820,4.577)--(7.929,4.104)--(8.038,3.653)--(8.146,3.234)%
  --(8.255,2.853)--(8.363,2.517)--(8.472,2.233)--(8.581,2.002)--(8.689,1.827)--(8.798,1.708)%
  --(8.906,1.644)--(9.015,1.631)--(9.124,1.667)--(9.232,1.745)--(9.341,1.860)--(9.449,2.004)%
  --(9.558,2.171)--(9.666,2.351)--(9.775,2.539)--(9.884,2.725)--(9.992,2.905)--(10.101,3.070)%
  --(10.209,3.216)--(10.318,3.339)--(10.427,3.435)--(10.535,3.502)--(10.644,3.539)--(10.752,3.546)%
  --(10.861,3.524)--(10.970,3.476)--(11.078,3.405)--(11.187,3.315)--(11.295,3.210)--(11.404,3.094)%
  --(11.513,2.974)--(11.621,2.853)--(11.730,2.736)--(11.838,2.628)--(11.947,2.533);
\gpcolor{color=gp lt color border}
\gpsetlinetype{gp lt border}
\draw[gp path] (1.196,8.381)--(1.196,0.616)--(11.947,0.616)--(11.947,8.381)--cycle;
%% coordinates of the plot area
\gpdefrectangularnode{gp plot 1}{\pgfpoint{1.196cm}{0.616cm}}{\pgfpoint{11.947cm}{8.381cm}}
\end{tikzpicture}
%% gnuplot variables

fig2.tex:

\begin{tikzpicture}[gnuplot]
%% generated with GNUPLOT 4.6p0 (Lua 5.1; terminal rev. 99, script rev. 100)
%% Tue 22 May 2012 10:34:12 PM EDT
\path (0.000,0.000) rectangle (12.500,8.750);
\gpcolor{color=gp lt color border}
\gpsetlinetype{gp lt border}
\gpsetlinewidth{1.00}
\draw[gp path] (1.196,0.616)--(1.376,0.616);
\draw[gp path] (11.947,0.616)--(11.767,0.616);
\node[gp node right] at (1.012,0.616) {-1};
\draw[gp path] (1.196,2.557)--(1.376,2.557);
\draw[gp path] (11.947,2.557)--(11.767,2.557);
\node[gp node right] at (1.012,2.557) {-0.5};
\draw[gp path] (1.196,4.499)--(1.376,4.499);
\draw[gp path] (11.947,4.499)--(11.767,4.499);
\node[gp node right] at (1.012,4.499) { 0};
\draw[gp path] (1.196,6.440)--(1.376,6.440);
\draw[gp path] (11.947,6.440)--(11.767,6.440);
\node[gp node right] at (1.012,6.440) { 0.5};
\draw[gp path] (1.196,8.381)--(1.376,8.381);
\draw[gp path] (11.947,8.381)--(11.767,8.381);
\node[gp node right] at (1.012,8.381) { 1};
\draw[gp path] (1.196,0.616)--(1.196,0.796);
\draw[gp path] (1.196,8.381)--(1.196,8.201);
\node[gp node center] at (1.196,0.308) {-10};
\draw[gp path] (3.884,0.616)--(3.884,0.796);
\draw[gp path] (3.884,8.381)--(3.884,8.201);
\node[gp node center] at (3.884,0.308) {-5};
\draw[gp path] (6.572,0.616)--(6.572,0.796);
\draw[gp path] (6.572,8.381)--(6.572,8.201);
\node[gp node center] at (6.572,0.308) { 0};
\draw[gp path] (9.259,0.616)--(9.259,0.796);
\draw[gp path] (9.259,8.381)--(9.259,8.201);
\node[gp node center] at (9.259,0.308) { 5};
\draw[gp path] (11.947,0.616)--(11.947,0.796);
\draw[gp path] (11.947,8.381)--(11.947,8.201);
\node[gp node center] at (11.947,0.308) { 10};
\draw[gp path] (1.196,8.381)--(1.196,0.616)--(11.947,0.616)--(11.947,8.381)--cycle;
\node[gp node right] at (10.479,8.047) {erf(x)};
\gpcolor{color=gp lt color 0}
\gpsetlinetype{gp lt plot 0}
\draw[gp path] (10.663,8.047)--(11.579,8.047);
\draw[gp path] (1.196,0.616)--(1.305,0.616)--(1.413,0.616)--(1.522,0.616)--(1.630,0.616)%
  --(1.739,0.616)--(1.848,0.616)--(1.956,0.616)--(2.065,0.616)--(2.173,0.616)--(2.282,0.616)%
  --(2.391,0.616)--(2.499,0.616)--(2.608,0.616)--(2.716,0.616)--(2.825,0.616)--(2.934,0.616)%
  --(3.042,0.616)--(3.151,0.616)--(3.259,0.616)--(3.368,0.616)--(3.477,0.616)--(3.585,0.616)%
  --(3.694,0.616)--(3.802,0.616)--(3.911,0.616)--(4.019,0.616)--(4.128,0.616)--(4.237,0.616)%
  --(4.345,0.616)--(4.454,0.616)--(4.562,0.616)--(4.671,0.616)--(4.780,0.616)--(4.888,0.616)%
  --(4.997,0.616)--(5.105,0.616)--(5.214,0.617)--(5.323,0.620)--(5.431,0.626)--(5.540,0.642)%
  --(5.648,0.675)--(5.757,0.741)--(5.866,0.862)--(5.974,1.067)--(6.083,1.387)--(6.191,1.848)%
  --(6.300,2.460)--(6.409,3.210)--(6.517,4.057)--(6.626,4.940)--(6.734,5.787)--(6.843,6.537)%
  --(6.952,7.149)--(7.060,7.610)--(7.169,7.930)--(7.277,8.135)--(7.386,8.256)--(7.495,8.322)%
  --(7.603,8.355)--(7.712,8.371)--(7.820,8.377)--(7.929,8.380)--(8.038,8.381)--(8.146,8.381)%
  --(8.255,8.381)--(8.363,8.381)--(8.472,8.381)--(8.581,8.381)--(8.689,8.381)--(8.798,8.381)%
  --(8.906,8.381)--(9.015,8.381)--(9.124,8.381)--(9.232,8.381)--(9.341,8.381)--(9.449,8.381)%
  --(9.558,8.381)--(9.666,8.381)--(9.775,8.381)--(9.884,8.381)--(9.992,8.381)--(10.101,8.381)%
  --(10.209,8.381)--(10.318,8.381)--(10.427,8.381)--(10.535,8.381)--(10.644,8.381)--(10.752,8.381)%
  --(10.861,8.381)--(10.970,8.381)--(11.078,8.381)--(11.187,8.381)--(11.295,8.381)--(11.404,8.381)%
  --(11.513,8.381)--(11.621,8.381)--(11.730,8.381)--(11.838,8.381)--(11.947,8.381);
\gpcolor{color=gp lt color border}
\gpsetlinetype{gp lt border}
\draw[gp path] (1.196,8.381)--(1.196,0.616)--(11.947,0.616)--(11.947,8.381)--cycle;
%% coordinates of the plot area
\gpdefrectangularnode{gp plot 1}{\pgfpoint{1.196cm}{0.616cm}}{\pgfpoint{11.947cm}{8.381cm}}
\end{tikzpicture}
%% gnuplot variables

Best Answer

This isn't a very good answer, but it's the best I've found so far. There seems to be some problem with tikzexternalize pushing strings into variables. I altered the code found in tikzexternalshared.code.tex (in texlive on Ubuntu, located in /usr/share/texmf/tex/generic/pgf/frontendlayer/tikz/libraries) to include an additional line.

Code before (lines 415-419):

\def\tikzexternalauxlock@setlock#1{%
        \immediate\openout\w@pgf@writea=\tikzexternal@realjob.auxlock
        \immediate\write\w@pgf@writea{\noexpand\def\noexpand\tikzexternallocked{#1}}%
        \immediate\closeout\w@pgf@writea
}

and code after:

\def\tikzexternalauxlock@setlock#1{%
        \immediate\write16{Value of \noexpand\w@pgf@writea: '\the\w@pgf@writea'}
        \immediate\openout\w@pgf@writea=\tikzexternal@realjob.auxlock
        \immediate\write\w@pgf@writea{\noexpand\def\noexpand\tikzexternallocked{#1}}%
        \immediate\closeout\w@pgf@writea

}

Just a little debugging statement that prints out the value of the file handle (in my case, '3'), caused the lualatex compiler to run without a hitch, at least with respect to the auxlock filename. It seems that without the \the call, the \w@pgf@writea variable doesn't properly purge itself (it had previously been used to hold the conversion system call), and ends up writing the name of the auxlock file over the beginning of the variable, without "zeroing it out" first, thus giving trailing characters that cause a file-open failure.

I still don't know what changed on my system that this behavior arose. Can anyone confirm this behavior, or explain the correct way to patch the tikzexternalize routines?

Related Solutions

[Tex/LaTex] Ploting a function using mplib in lualatex

This is how I would do it in ConTeXt. I don't know if similar functionality is available in a LaTeX package. Basically, I do the calculations in lua and write the result inside a \startMPcode .. \stopMPcode environment.

\startluacode
  require("math")
  local sin = math.sin
  local cos = math.cos 
  local pi  = math.pi 

  local function scale(x) 
    return x .. " * 1cm"
  end
  local function pair(x,y) 
    return "(" .. scale(x) .. "," .. scale(y) .. ")"
  end

  local function point(f,x)
    return pair(x, f(x))
  end

  userdata = userdata or {}

  function userdata.draw_function(f, a, b, n) 
    local step = (b-a)/n
    local path = {}
    local i = 0 
    for x = a, b, step do 
      path[i] = point(f,x) 
      i = i + 1
    end  
    path = table.concat(path, "--")

    context("draw " .. path .. " withpen pencircle scaled 2bp;")
  end

  function userdata.draw_x_axis(from, to)
      context(" drawarrow " .. pair(from,0) .. " -- " .. pair(to,0) .. "; ")
      context(" label.rt ( btex $x$ etex , " .. pair(to,0) .. ") ;")
  end

  function userdata.draw_y_axis(from, to)
      context(" drawarrow " .. pair(0, from) .. " -- " .. pair(0,to) .. "; ")
      context(" label.top ( btex $y$ etex , " .. pair (0,to) .. ") ;")
  end

  function userdata.plot()

    userdata.draw_x_axis(-2, 6.5) 
    userdata.draw_y_axis(-2.2, 2.2)


    local f = function (x) 
      return sin(2*x) + cos(x)
    end

    userdata.draw_function(f, 0, 2*pi, 40)
  end

\stopluacode

\starttext
  \ctxlua
    {context.startMPcode() ;
      userdata.plot() ;
     context.stopMPcode() ; }
\stoptext

However, this assumes that everything that is written inside teh userdata.plot() function is MP code. If you also want that function to print stuff to the TeX stream, then you can store all the MP code inside a \startMPdrawing and \stopMPdrawing environment and retrieve them using \getMPdrawing.

\startluacode
  require("math")
  local sin = math.sin
  local cos = math.cos 
  local pi  = math.pi 

  local function scale(x) 
    return x .. " * 1cm"
  end
  local function pair(x,y) 
    return "(" .. scale(x) .. "," .. scale(y) .. ")"
  end

  local function point(f,x)
    return pair(x, f(x))
  end

  userdata = userdata or {}

  function userdata.draw_function(f, a, b, n) 
    local step = (b-a)/n
    local path = {}
    local i = 0 
    for x = a, b, step do 
      path[i] = point(f,x) 
      i = i + 1
    end  
    path = table.concat(path, "--")

  context.startMPdrawing()
    context("draw " .. path .. " withpen pencircle scaled 2bp;")
  context.stopMPdrawing()
  end

  function userdata.draw_x_axis(from, to)
    context.startMPdrawing()
      context(" drawarrow " .. pair(from,0) .. " -- " .. pair(to,0) .. "; ")
      context(" label.rt ( btex $x$ etex , " .. pair(to,0) .. ") ;")
    context.stopMPdrawing()
  end

  function userdata.draw_y_axis(from, to)
    context.startMPdrawing()
      context(" drawarrow " .. pair(0, from) .. " -- " .. pair(0,to) .. "; ")
      context(" label.top ( btex $y$ etex , " .. pair (0,to) .. ") ;")
    context.stopMPdrawing()
  end

  function userdata.plot()
    userdata.draw_x_axis(-2, 6.5) 
    userdata.draw_y_axis(-2.2, 2.2)


    local f = function (x) 
      return sin(2*x) + cos(x)
    end

    userdata.draw_function(f, 0, 2*pi, 40)
  end

\stopluacode

\starttext
  \ctxlua
    { context.resetMPdrawing() ;
      userdata.plot() ;
      context.MPdrawingdonetrue() ;
      context.getMPdrawing() ; }
\stoptext

[Tex/LaTex] Easiest way to plot matrix image

As the sample matrix datasets(131*131) are large in size LuaLaTeX -shell-escape approach was adopted and pdflatex fails due to memory limitations. I have retained the TeX memory defaults on TeXLive 2012 frozen. In view of your real datasets of size (1000x500) points. I made some points to help you.
TeX memory problems in pgfplots can be resolved by(More info at Section 6.1 pgfplots manual revision 1.8, 17/3/2013)

1)How to expand TeX's "main memory size"? (pgfplots memory overload) and How can one predict pgfplots memory overload?

2)Downsampling the data using gnuplot or sed as discussed in pgfplot: plotting a large dataset.

3)Export separate figure pdf's using pgfplots externalize library to reduce the compilation time and avoid memory problems for large documents.

4)Alternatively use fully gnuplot solution using gnuplottex package via improved terminal exports epslatex, pdf, and lua/tikz.

gnuplot lua/tikz terminal driver

"The lua terminal driver creates data intended to be further processed by a script in the lua programming language. At this point only one such lua script, gnuplot-tikz.lua, is available. It produces a TeX document suitable for use with the latex TikZ package. Other lua scripts could be written to process the gnuplot output for use with other TeX packages, or with other non-TeX tools. set term tikz is shorthand for set term lua tikz. As decribed above, it uses the generic lua terminal and an external lua script to produce a latex document" from gnuplot 4.6 documentation

Examples:

A tikz terminal can export full-plot.tex of plot like in this TeXample.net example and gnuplottikz example

Hoping this works for you.

Using pgfplots (invoking gnuplot) and it's groupplot library. on 131*131 matrix dataset provided by OP

\documentclass[preview=true,12pt,border=2pt]{standalone}
\usepackage{pgfplots}
\pgfplotsset{compat=newest}
\usepgfplotslibrary{groupplots} 
%\usepgfplotslibrary{external}
%\tikzexternalize% activate externalization!
% same matrix data used for all four figures for illustration
% code compiled with lualatex -shell-escape, gnuplot 4.4.3 and pgfplots 1.8 
% Matrix dataset(131*131) in "mat-data.dat" (provided by OP in comment). 
\begin{document}
\begin{tikzpicture}
\begin{groupplot}[view={0}{90},colorbar,colormap/bluered,colorbar style={%
ytick={-19,-18,-17,-16,-15,-14,-13,-12,-11}},label style={font=\small},group style={group size=2 by 2,horizontal sep=3cm},
height=3.5cm,width=3.5cm,footnotesize]
\nextgroupplot % First Figure
\addplot3[raw gnuplot,surf,shader=interp]
            gnuplot[id={surf}]{%
set pm3d map interpolate 0,0;
splot 'mat-data.dat' matrix using 1:2:(log($3));}; %natural logarithm
\nextgroupplot % Second Figure
\addplot3[raw gnuplot,surf,shader=interp]
            gnuplot[id={surf}]{%
set pm3d map interpolate 0,0;
splot 'mat-data.dat' matrix using 1:2:(log($3));};
\nextgroupplot % Third Figure
\addplot3[raw gnuplot,surf,shader=interp]
            gnuplot[id={surf}]{%
set pm3d map interpolate 0,0;
splot 'mat-data.dat' matrix using 1:2:(log($3));};
\nextgroupplot % Fourth Figure
\addplot3[raw gnuplot,surf,shader=interp]
            gnuplot[id={surf}]{%
set pm3d map interpolate 0,0;
splot 'mat-data.dat' matrix using 1:2:(log($3));};
\end{groupplot}
\end{tikzpicture}
\end{document}

code compiled with lualatex -shell-escape, gnuplot 4.4.3 and pgfplots 1.8

enter image description here

Alternative Approach(option 4 above): Using fully gnuplot based on gnuplottex package

code compiled with pdflatex -shell-escape, gnuplot 4.4.3 and gnuplottex(version October 2, 2012)

enter image description here

\documentclass[preview=true,border=2pt]{standalone}
\usepackage{gnuplottex} 
\begin{document}    
\begin{gnuplot}[terminal=epslatex,terminaloptions={font ",7"}]
set tmargin 0       # set white top margin in multiplot figure
set bmargin 1       # set white bottom margin in multiplot figure  
set lmargin 0
set rmargin 0 
set xrange [0:130]; # x and y axis range 
set yrange [0:130];
set cbrange [-19:-12]; # colorbox range  
unset key;             # disables plot legend or  use "notitle"  
set palette model RGB defined (0 '#0000B4',1 '#00FFFF',2 '#64FF00',3 '#FFFF00',4 '#FF0000',5 '#800000');         # hex colormap matching pgfplots "colormap/bluered"  
set pm3d map;       # `splot` for drawing palette-mapped 3d colormaps/surfaces
set pm3d interpolate 0,0; # interpolate optimal number of grid points into finer mesh, and          
                          # color each quadrangle with 0,0
set multiplot layout 2,2 rowsfirst scale 0.9,1.2;  # subplots 2 by 2
# First Figure
splot 'mat-data.dat' matrix using 1:2:(log($3)); # matrix data with log(z-axis)
# Second Figure
splot 'mat-data.dat' matrix using 1:2:(log($3)); 
# Third Figure
splot 'mat-data.dat' matrix using 1:2:(log($3)); 
# Fourth Figure
splot 'mat-data.dat' matrix using 1:2:(log($3)); 
unset multiplot;
\end{gnuplot}
\end{document}

Alternative Approach: Reading from mat-data.dat file directly in pgfplots

I have failed to get result in this way. Anybody can give their feedback. \addplot3[surf,mesh/cols=131,mesh/ordering=rowwise,shader=interp] file {mat-data.dat};

Best Answer

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