# [OS X TeX] Latex symbol for "define equal"

Art Werschulz agw at comcast.net
Sat Aug 18 22:01:41 EDT 2018

Hi.

> On Aug 18, 2018, at 7:21 AM, Themis Matsoukas <tmatsoukas at icloud.com> wrote:
>
> What is the accepted symbol in math for “equal by definition” and how to get in latex? I have been using \equiv but I have seen “:=“, equal sign with a triangle on top, or “def” on top of =.

I'm used to seeing := as the notation for "is defined to be".  You sometimes find =: for "defines", when it's more natural to have the thing being defined at the end, rather than at the beginning, of a math passage.

The centercolon and mathtools LaTeX packages are used to fix symmetry issues with := .

BTW, the last time I used \equiv for defining something (something like $E_{d,\gamma}f\equiv f$, a referee swatted it down.  :=)

Art Werschulz
agw at comcast.net