![[equation]](eqn-109.gif)
italic.
Although this could be done by surrounding the appropriate parts
with
.EQ
and
.EN,
the continual repetition of
.EQ
and
.EN
is a nuisance.
Furthermore, with `-ms',
.EQ
and
.EN
imply a displayed equation.
In a mathematical document,
it is necessary to follow mathematical conventions
not just in display equations,
but also in the body of the text,
for example by making variable names like italic.
Although this could be done by surrounding the appropriate parts
with
.EQ
and
.EN,
the continual repetition of
.EQ
and
.EN
is a nuisance.
Furthermore, with `-ms',
.EQ
and
.EN
imply a displayed equation.
EQN
provides a shorthand for short in-line expressions.
You can define two characters to mark the left and right ends
of an in-line equation, and then type expressions right in the middle of text
lines.
To set both the left and right characters to dollar signs, for example,
add to the beginning of your document the three lines
.EQ
delim %%
.EN
Having done this, you can then say things like
Let %alpha sub i% be the primary variable,
and let %beta% be zero.
Then we can show that %x sub 1% is %>=0%.
This works as
you might expect _
spaces, newlines, and so on are significant
in the text, but not in the equation part itself.
Multiple equations can occur in a single input line.
Enough room is left before and after a line that contains
in-line expressions
that something like
![[equation]](eqn-110.gif)
does not interfere with the lines surrounding it.
To turn off the delimiters,
.EQ
delim off
.EN
Warning: don't use braces, tildes, circumflexes, or double quotes as delimiters _
chaos will result.