With newtxmath 2016/10/15 v1.51 and apacite 2013/07/21 v6.03, if newtxmath is loaded before apacite, we get errors about \BIP, \BIn etc already defined:



! LaTeX Error: Command \BIP already defined.
           Or name \end... illegal, see p.192 of the manual.

If apacite is loaded before newtxmath, no error is thrown. The references look fine i.e. various APAcite strings e.g. \BIP is still "in press".

Should this be considered a bug? Would there be any side effects to either packages if apacite is loaded before newtxmath?

  • 2
    Looks like it: newtxmath defines a whole load of \BI<letter> commands.
    – Joseph Wright
    Commented Nov 7, 2016 at 15:45
  • 1
    I filed an issue report to M. Sharpe.
    – egreg
    Commented Nov 7, 2016 at 16:48

1 Answer 1


The newtxmath package defines the commands \BIA to \BIZ and \BIa to \BIz for “bold italic letter”.

In my opinion it shouldn't: users can and should use bm instead.

However, there's apparently no problem in doing like you ended up with.

Indeed, apacite.sty defines \BIP, then newtxmath overrides this definition, but apacite also loads an .apc file at begin document and english.apc has

\renewcommand{\BIP}{in press}%            % ``in press''
\renewcommand{\BIn}{In}%                  % for ``In '' editor...

so the two macros that are overwritten by newtxmath get overwritten again.

The problem could show up if an unsupported language is used, that is not among Dutch, Finnish, German, Spanish, English, French, Greek, Norwegian and Swedish. In those cases the user should supply appropriate \renewcommand for those two macros anyway.


As of version 1.513 of newtxmath, the \BIx (x representing any letter) are not defined by default any more and are only available if the useBImacros option is passed at package loading.

Changes in version 1.513
Changed availability of \BIx macros to work around conflicts with other packages. They may now be enabled with the option useBImacros, otherwise thay are disabled.

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