This example either divides or multiplies the symbol $1 by
a factor of two, depending on the value of the NOE energy
($NOE). In the first case, 40 steps of minimization are
carried out, whereas in the latter case, 100 steps of minimization
are carried out. Note that the indentation is arbitrary but
can make the input file more readable.
if ($NOE > 10.0) then
evaluate ($1=$1/2.0)
minimize powell
nstep=40
end
else
evaluate ($1=$1*2.0)
minimize powell
nstep=100
end
end if

*Xplor-NIH 2023-11-10*