The functions in this section are actual functions; they compose their arguments according to the current language and other display modes, then return a certain measurement of the composition as an integer.
The
cwidth function measures the width, in characters,
of a composition. For example, ‘cwidth(a + b)’ is 5, and
‘cwidth(a /
b)’ is 5 in Normal mode, 1 in Big mode, and
11 in TeX mode (for ‘{a \over
b}’). The argument may involve the
composition functions described in this section.
The
cheight function measures the height of a
composition. This is the total number of lines in the argument's
printed form.
The functions cascent and
cdescent measure the amount of the height that is
above (and including) the baseline, or below the baseline,
respectively. Thus ‘cascent(x) +
cdescent(x)’ always equals
‘cheight(x)’. For a one-line formula like
‘a + b’,
cascent returns 1 and cdescent returns
0. For ‘a / b’
in Big mode, cascent returns 2 and
cdescent returns 1. The only formula for which
cascent will return zero is
‘cvspace(0)’
or equivalents.