If you use a comma in maths mode, you get a small space after it; this
space is inappropriate if the comma is being used as a decimal
separator. An easy solution to this problem is to type (in maths
mode) 3{,}14
instead of typing 3,14
. However, if your language's
typographic rules require the comma as a decimal separator, such usage
can rapidly become extremely tiresome. In such cases it is probably
better to use the icomma package. The packages ensures that
there will be no extra space after a comma, unless you type a space
after it (as in f(x, y)
, for instance), in which case the usual
small space after the comma appears.
This question on the Web: http://www.tex.ac.uk/cgi-bin/texfaq2html?label=dec_comma