# Is there a sign for "according to?"

There are signs in mathematics for "therefore" and "because," which are $\therefore$ and $\because$ respectively.

However, another frequently-used expression is "according to." Is there any symbol for that?

• Do you mean it like "according to [reference]" or "according to Eq. (X)", or something mathematical? Could you provide an example? Sep 4, 2016 at 17:24
• @Lovsovs I mean both, as a matter of fact. I would have thought that it would be the same, but even if it isn't I'd like to know, as I haven't come across anything like it before. Sep 4, 2016 at 17:30
• Sometimes the clearest route is simply using "according to...". Clarity isn't guaranteed by finding symbolic notation for every notion. When meaning is dependent on context (according to Plato...), according to figure 1.a..., etc Sep 4, 2016 at 17:31
• Don't be afraid to use some actual words. Sep 4, 2016 at 17:33
• Instead of "according to Eq. $(3)$", you can also often write "by Eq. $(3)$". Less typing, and using both gives additional variation of formulation. Sep 4, 2016 at 17:58

No, there isn't, and it isn't good practice to use mathematical/formalistic symbols in the middle of a sentence.

For instance:

"Now, Eq. (1) $\rightarrow$ that Eq. (2) is $\sim$ true,"

"Now, Eq. (1) implies that Eq. (2) is false,"

only makes the sentence more obscure. You could write out every sentence as a logical statement, but ask yourself, "what text would I rather read?" Your audience probably would choose the same.

• Thanks for the answer. On a side note, should I use a single or a double arrow for "implies that?" Sep 4, 2016 at 17:37
• @SkeletonBow Single; the double is a "double implication," which has a different (stronger) meaning. Sep 4, 2016 at 17:38
• @Lovsovs OP means "$\implies$" versus "$\to$", perhaps.
– Pedro
Sep 4, 2016 at 17:54
• @Lovsovs What’s the meaning of the double implication? Oh, you mean the equivalence arrow “⇔”, right? Sep 4, 2016 at 17:55
• @SkeletonBow They often mean the same, but when doing some algebraic manipulations, I'd actually stick to using $\implies$. $\rightarrow$ can also be used, but is also used when defining functions ($f:\mathbb{R}\rightarrow \mathbb{R}^2$). See this wiki for more details. Sep 4, 2016 at 18:44

There is a Latin abbreviation sec. from secundum, meaning "following" or "in accordance with", sometimes used as "sec. Smith", which means "according to Smith".

• Interesting! Would it be applicable for something like sec. Eq (1) or sec. [reference to rule]? Sep 4, 2016 at 21:58
• @SkeletonBow I have no idea! If not for my exceptional google-fu, I wouldn't even know about this abbreviation. ;) Sep 4, 2016 at 22:02
• @SkeletonBow : You should only use this abbreviation if you do not want people to know what you mean. Sep 5, 2016 at 3:10