OpenBSD-4.6/usr.bin/learn/lib/eqn/L2.2e

#print
Make the two equations in "Example" look like these two,
then type "ready".

#once #create Ref
.ND
.LP
.EQ (1.1)
PI ~=~ ( pi sub 1 , pi sub 2 ,..., pi sub n )
.EN
.EQ (1.2)
pi bar ~=~ sum ( alpha , beta )
.EN
.pl 1
#once #create Example
.ND
.LP
.EQ
PHI = ( phi sub 1 , phi sub 2 ,..., phi sub n )
.EN
.EQ
phi bar = sum (A,B)
.EN
.pl 1
#
#once neqn Ref | nroff >X1 &
#once neqn Ref | nroff -T$term %s/tinyms -
#user
neqn Example | nroff >X2
#cmp X1 X2
#fail
Don't forget equation numbering and spaces
where needed.  Print file "Chars" if you've forgotten
the character names.
#log
#next
2.1f