Is it possible to define macro with numeric name and without at the same time?

Question

I want to define variable with letters and with numerical numbers. But the variable have same name with and without numeric value. Here is an example:

Basically I want to define

  \def\lam{\lambda}
  \newcommand{lam}{\lambda}
  \def\lam#1{\lambda^{#1}}

In the expression I have

  F = \lam + \lam2 + \lam3

The output should be

  F = \lambda + \lambda^2 + \lambda^3

short answer no, use \lamb and \lamc technically you can re-classify digits as letters so \lam2 works, but then you break most of the rest of latex. — David Carlisle, Jun 12 '20 at 17:08

score 2 · Accepted Answer · answered Jun 12 '20 at 17:57

2

For example, you can do this:

\newcount\tmpnum
\def\lam{\lambda\afterassignment\lamA\tmpnum=0}
\def\lamA{\ifnum\tmpnum=0 \else ^{\the\tmpnum}\fi}
$ F = \lam + \lam2 + \lam3 $

answered Jun 12 '20 at 17:57

wipet

74,238

1

This is working perfectly. However to overcome this I have to add three lines of command!! – BabaYaga Jun 12 '20 at 18:25
2

@Boogeyman Only one \def line in needed for each new similar command, for example \def\delt{\delta\aftrerassignment\lamA\tmpnum=0}. In other words, the line 1 and 3 from the code above is common for each such macros. – wipet Jun 12 '20 at 18:35
one more question, if my expression also contains \lam and \lam1 , is there any way to force them to have same output? – BabaYaga Jun 13 '20 at 10:33
1

@Boogeyman Yes, define \def\lamA{\ifnum\tmpnum>1 ^{\the\tmpnum}\fi} – wipet Jun 13 '20 at 15:08

score 1 · Answer 2 · answered Jun 12 '20 at 17:19

1

I found how to check if argument is a number here. And after you just output if that's not a number:

\documentclass{article}
\newcommand{\lam}[1]{%
  \ifnum0<0#1\relax
    $\lambda^{#1}$%
  \else
     $\lambda$~{#1}%
  \fi
}
\begin{document}
F = \lam + \lam2 + \lam3
\end{document}

answered Jun 12 '20 at 17:19

Denys Potapov

962

1

I like this solution. But this is causing some problem when I do say `\frac{1}{\lam}'. – BabaYaga Jun 12 '20 at 18:25
Basically what you are doing is to replace \lam by \lam^{} like @David Carlisle has said in the comment. – BabaYaga Jun 12 '20 at 18:30
@Boogeyman no. This does not make empty superscripts – David Carlisle Jun 12 '20 at 18:33
3

it would be better to take the $ and ~ out of the definition and put $ around the expression otherwise spacing will be wrong for = and + – David Carlisle Jun 12 '20 at 18:36

Is it possible to define macro with numeric name and without at the same time?

2 Answers2