LaTeX math symbol macro

Question

I've long had a dream of creating a "consistent comparison" operator to use in my homework (in LaTeX). That is, in some long derivation, we might want to know how $a$ compares to $b$, and although this is totally contrived, an example might read ``` \begin{align*} a &? b \ f(a) &? f(b) \ f(a) &= f(b) 	ext{by assumption} \ \implies a &= b \end{align*} ``` That is, we start by saying, "this comparison should be consistent throughout the derivation", and then we later see that ? (the comparison operator) can be replaced with =. This notation is clearly crappy, and now that I'm doing more group work, it'd be nice to have something that's a bit more graphically intuitive. I've got a pipe dream of a little circle with a question mark inside or on top of it. Trouble is, I have no idea how to do individual character sizing/alignment in LaTeX macros. So far, I've come up with ``` \def\mycomparator{\circ^{\!\!\!?}\,} $a \mycomparator b$ ``` (that is, a small circle with a superscript questi…

Accepted Answer

Try the following (not tested):

```

ewcommand{\mycomparator}{\stackrel{?}{\circ}}
```

Also look up \mathrel, it can be used to make arbitrary symbolds into a relation for correct math spacing.

Mathematically your idea is not so brilliant, as different relations obey different rules. For an example, multiply both sides of an inequation by a negative number.

Actually, standard practice would use an uppercase R for a general relation, i.e. \mathrel{R} for proper spacing. You can use subsequent letters or indices if you need more than one.

For a general transitive relation I'd use some nonstandard comparison symbol like \preceq or \prec, depending on whether it is reflexive or not.

\circ is normally used for a general binary operation, or for function composition.

LaTeX math symbol macro

Solution

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