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

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

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

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Search "Geometrically equal to" on this page

https://www.w3.org/TR/MathML2/isoamsr.html

I don't know what that means, but it's the right symbol.

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  • $\begingroup$ It means same size and shape. $\endgroup$ – L. Scott Johnson Nov 4 '20 at 19:14
  • $\begingroup$ Is that congruent? $\endgroup$ – J. W. Tanner Nov 4 '20 at 19:33
  • $\begingroup$ Compare to the similar symbol in the codepoint below that one. I'm pretty sure Somos's comment was right that the meaning here is "approximately equal to" and not "geometrically equal to" (whatever that was intended to mean). In general, the Unicode glosses are not a good reference for all usages of a symbol. $\endgroup$ – Mark S. Nov 4 '20 at 23:39

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