Hi Bruce (and Morten as, I think, the prime suspect re math style) This is not an answer but I think I see what has happened. amsmath has an internal command \@genfac and this is what has been used, in some sense, as the basis for the user-command in mathstyle. I refrain from comment of whether this change was a Good Thing (™). It could be that the required contents of the 'style' parameter are not compatible so more work may be needed than a change of parameter ordering. Chris From amsmath.pdf: \@genfrac takes the preceding arguments and reads the numerator and de- nominator. Note that there’s no convenient way to make the numerator and denominator contents displaystyle, through this interface. Args: #1 mathstyle, #2 fraction primitive, #3 delimiters and rule thickness, #4 numerator, #5 denominator. Sent from my iPud (\~/) > On 28 Oct 2014, at 17:29, Bruce Miller <[log in to unmask]> wrote: > > Hi all; > Not sure whether this is the right place for this > message, but a colleague is using breqn, which > pulls in a lot of l3kernel stuff, and also mathstyle. > > Unfortunately, it appears that the package mathstyle > redefines \genfrac with a different argument order > than amsmath. (and worse, wants to be loaded after > amsmath, so you're stuck with the redefinition) > > mathstyle's api seems to be: > \genfrac{style}{open}{close}{thickness}{numer}{denom} > while amsmath's is > \genfrac{open}{close}{thickness}{style}{numer}{denom} > > Is there a good reason for this? > > thanks > bruce