In a two-column document, I use the
figure* environment to place a wide equation in a one-column format. It works fine, but the equation floats to the next page. What can I do to avoid this?
You need to move the
figure* earlier in your source file so it lands on the page you want.
You may need to say
(or some number instead of 2)
after to get the correct equation number relative to the final position.
It is not ideal but it is a hard limit in the latex float algorithm it can not place two-column floats on the same page (as it has already committed to the page height for that page.) Nor (except at the start of the two column region) does it offer a static non floating area into which you can put wide material, so some hand correction to the numbering is currently necessary.