# What does $\doteqdot$ mean?

I am reading the following document of Solitary waves page $$14$$. And I found the following symbol $$\doteqdot$$.

What does $$\doteqdot$$ mean? For example: $$y_t \doteqdot -c_0y_x$$

• The relevant information might already be here, but I think that that page you linked is behind a paywall. – Gae. S. Nov 4 '20 at 19:03
• This is Unicode 2251, called "GEOMETRICALLY EQUAL TO". – GEdgar Nov 4 '20 at 19:35
• @Somos You could post that as an answer – Mark S. Nov 4 '20 at 23:36

After the very first equation (1.1) is this line

breaking occurs for a≑d. ...

so I think that it means "approximately equal to" which is usually written with ≈. I don't know why the author decided to use this symbol. It must be a rare usage because I had not seen it used before.