On Tue, 6 Jun 2006, Taco Hoekwater wrote:

Aditya Mahajan wrote:

...

Hi, I am confused why the following definition does not work as expected.

\def\PM{\dosingleempty\doPM} \def\doPM[#1]{\iffirstargument P_{M_{#1}} \else P_{M_t}\fi}

\starttext Why is $\widetilde \PM[T]$ not the same as $\widetilde P_{M_T}$ \stoptext

The argument to \widetilde cannot be a macro that requires arguments, that just won't work. If you want the accent on top of a single character, you have to give it a single argument. It is possbile to do so, like this:

\def\PM{P\dosingleempty\doPM} \def\doPM[#1]{\iffirstargument _{M_{#1}}\else _{M_t}\fi} \let\normalwidetilde\widetilde \def\widetilde{\expandafter\normalwidetilde}

Thanks. I will test around to see it this has undesired side-effects. If something else breaks, I will define \def\ewidetilde{\expandafter\widetilde} and use \ewidetilde before \PM.

But it is better to create a new set of macros \widetildePM.

That is what I was doing till now. But I have a lot of costructs like this, \PM[t] <=> P_{M_t}, \PYM <=> P_{Y_t,M_{t-1}}, \PYMS <=> P_{Y_t,M_{t-1},S_t} and so on and all of them can have widetilde and wildehat. Gets kind of boring to define \tPM for widetilde \hPM for widehat for all of them. Thanks, Aditya