Bottom margin vs. descenders question

Doug McKenna doug at
Sun Jul 5 22:23:51 CEST 2020


The bottom margin is not based on a multiple of \baselineskip or similar.  It is based on measuring 720 pixels down from the top of an 8.5" by 11" inch PDF page in PostScript coords (72/inch), to get to the bottom 1" margin.

Doug McKenna

----- Original Message -----
From: "Axel E. Retif" <axel.retif at>
To: "doug" <doug at>, "texhax" <texhax at>
Sent: Sunday, July 5, 2020 12:01:15 PM
Subject: Re: Bottom margin vs. descenders question

On 7/5/20 11:52 AM, Doug McKenna wrote:

> Enclosed is a screenshot of what I have tried to output in my program. 
> The red lines have been superimposed onto the PDF to show where the 
> margin bounds are.  This seems a perfect example of what has just been 
> discussed: a math formula with large delimiters on the bottom line of 
> the page that descend quite a bit into the margin area in order to 
> maintain the baseline of the bottom line on every page at the same 
> vertical position.  It is typeset properly, even though it breaches the 
> margin.  I believe this was typeset with TeX/LaTeX.

If the red line marks the height of the page *in multiples* of the 
baselineskip, then indeed the delimiters are protruding *a lot*. In that 
case the descenders of p's and q's of the confronted page would coincide 
with the parentheses of the formula number (2).

But maybe (La)TeX is balancing the baseline of the formula and the 
protrusion of the delimiters; in this case, the baseline of the formula 
would be higher than the baseline of text in the confronted page. One 
has to see the confronted page or measure any other page that ends with 
text to see what's happening.

Be it as it may, those delimiters of the formula are larger than 
desirable. In the TeXbook, p. 149, Knuth advises to use \bigl(, \Bigl(, 
\biggl(, etc., and corresponding \biggr), etc., instead of \left( and 



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