Wikipedia:Reference desk/Archives/Mathematics/2017 July 1

Welcome to the Wikipedia Mathematics Reference Desk Archives
The page you are currently viewing is an archive page. While you can leave answers for any questions shown below, please ask new questions on one of the current reference desk pages.

July 1

Symbols ⌠ ⌡ (top half integral and lower half integral)

What are these symbols used for in mathematics? DTLHS (talk) 21:42, 1 July 2017 (UTC)

My guess is that it has to do with typography. The integral symbol is normally taller than the rest of the font, so it is in two parts. Bubba73 ^{You talkin' to me?} 01:41, 2 July 2017 (UTC)

Integral symbol#Fundamental symbol says "The original IBM PC code page 437 character set included a couple of characters ⌠ and ⌡ (codes 244 and 245, respectively) to build the integral symbol. These were deprecated in subsequent MS-DOS code pages, but they still remain in Unicode (U+2320 and U+2321, respectively) for compatibility". Rojomoke (talk) 05:30, 2 July 2017 (UTC)

Also note that one or more vertical bars could be inserted beween the two ends of the integral sign to make the desired height. For example:

     ⌠  dx
     | ----- = ln x + C
     ⌡   x

--76.71.5.114 (talk) 21:33, 2 July 2017 (UTC)

This is a very good point. Lots of research monographs from as recent as the 1980s still used that type of layout. Very unpleasant to read, but doing it right would have been cost prohibitive at the time. SemanticMantis (talk) 16:14, 3 July 2017 (UTC)