Open a .tex file, modify it in MATLAB, and then save it in a .tex file again (+ possibly compile it)

Let's say I have a tex file, say MWE.tex, whose content is

\documentclass[11pt]{report}
\RequirePackage{amssymb, amsfonts, amsmath, latexsym, verbatim, xspace, setspace}
\RequirePackage{tikz, pgflibraryplotmarks}  
\usepackage[margin=1in]{geometry}

\begin{document}
In this report we use x = VARX and y = VARY.
\end{document}

I would like to open in MATLAB, substitute VARX and VARY with values that come from some functions and save them in another .tex file. For instance VARX is the result of randi(10) and VARY is the result of randi(5).

What's the simplest solution to do this?

Would it also be possible to launch the latex compiler from Matlab? How?

Answer 1

[Nick]

I think I got it

text = fileread('MWE.tex');
newtext = strrep(text,'VARX',num2str(randi(10)));    
newtext = strrep(newtext,'VARY',num2str(randi(5)));    

fileID = fopen('newMWE.tex','w');
fprintf(fileID,'%s',newtext);
fclose(fileID);

command = 'pdflatex newMWE.tex';
[status,cmdout] = system(command)

[Lisa]

Thank you!

Answer 2

[Walter Roberson]

The simplest way is to open the file for reading, open a different file for writing, and copy lines from the input to the output until you reach the line you want to change, at which point you send the changed line to output instead of copying. After that resume copying until you reach the end of the input; then close both files.

Changing a text file "in place" can only work if the changed version has exactly the same size as what is being changed. Most of the time that isn't the case.

[Walter Roberson]

You can use system() to invoke the tex compiler. You can construct the string to system() by using sprintf() if you want to include the content of variables.