The error in question is:

! Undefined control sequence.
\ifthenelse #1#2#3->\let \bbl@temp@pref 
                                    \pageref \let \pageref \org@pageref 
l.19 \date{\today}




I would like for \thedate to not print e.g. September 10. 2018 but rather 2018-09-10.


1 Answer 1


I tested your example with all versions of TeX Live from 2012 to 2018. Up to 2014 the error is different, but still the code doesn't work.

This is because memoir has a different definition of \date than the standard classes. It performs \protected@xdef on the argument to \date in order to define \thedate so that footnotes or \thanks commands disappear from it and this is the problem: isodate redefines \today in such a way that it doesn't survive \protected@xdef.

You solve the issue with

  • So what does the error actually mean? I am getting the same error in beamer, using pgfplots and explicitely calling visualizaion depends on={value \ifthenelse{\thisrow{v}<90}{white}{black} \as \tcolor} which throws the above error and I have no idea how to debug this. Is there some straight-forward solution or do I have to post a separate question? Dec 11, 2018 at 9:27
  • @BjarneThorsted A separate question is in order with more details.
    – egreg
    Dec 11, 2018 at 10:11
  • I have created a question, Obscure error with conditional formatting in pgfplots Dec 11, 2018 at 10:18

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