Doc: add mathtools to imglatex. Use latex_additional_files instead of…

… loop

src/conf.py

@@ -264,20 +264,19 @@
 
 # Additional stuff for the LaTeX preamble.
 latex_elements['preamble'] = '\\usepackage{amsmath}\n\\usepackage{amssymb}\n\\usepackage[retainorgcmds]{IEEEtrantools}\n\\usepackage{mathtools}\n'
+latex_additional_files = ['docs/sphinx/latex_macros.sty']
 
 bibtex_bibfiles = ['docs/sphinx/biblio_wave.bib']
 
 #####################################################
 # add LaTeX macros
 
 f = open('docs/sphinx/latex_macros.sty')
-imgmath_latex_preamble = ""
+imgmath_latex_preamble = "\\usepackage{mathtools}"
 imgmath_image_format = 'svg'
 imgmath_font_size = 14
 
 for macro in f:
-    # used when building latex and pdf versions
-    latex_elements['preamble'] += macro + '\n'
     # used when building html version
     imgmath_latex_preamble += macro + '\n'