# is there an option in latexdiff to ignore whole environments?

I need to highlight the difference between two rather complex math tex-files and get a lot of errors. The files are complex in the math equations, fair enough to get errors, but what if I would like latexdiff to only compare the text OUTSIDE the \begin{align} ... \end{align} environment? Can one specify to exclude/ignore certain environments?

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Yes there is a way to do this. latexdiff has a class of environments that it regards as pictures and which it does not check. The value is stored in PICTUREENV and its default is (?:picture|DIFnomarkup)[\w\d*@]*. Writing a config file ld.cfg containing

PICTUREENV=(?:picture|DIFnomarkup|align)[\w\d*@]*

adds the align environment to this list. If this config file is placed in the current directory you can now run

latexdiff -c ld.cfg old.tex new.tex >diff.tex

and the content of your align environments will now be ignored.

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Note that you do not need to put it in a separate config file. You could also do latexdiff --config="PICTUREENV=(?:picture|DIFnomarkup|align)[\w\d*@]*" –  Rabarberski Aug 27 '13 at 9:11
@Rabarberski Indeed, remember double dash before config. However, the command starts getting long and one has to be careful about escaping. –  Andrew Swann Aug 27 '13 at 9:16