13.3 Features for scientific programming
FWEB contains a few features particularly intended for scientific
programming.
-  Several built-in functions generate numerical constants.  See ‘$PI’
($PI) and ‘$E’ ($E).
 -  Several built-in functions perform mathematical manipulations.  See
‘$EXP’ ($EXP), ‘$POW’ ($POW), ‘$SQRT’
($SQRT), ‘$LOG’ ($LOG), ‘$LOG10’ ($LOG10), 
‘$MAX’ ($MAX), and ‘$MIN’ ($MIN).
 -  The do-loop macro ‘$DO’ may be useful.  See $DO.
 -  C-style array indices can be used by means of the ‘-n)’ option.
See -n). 
 -  An active bracket feature helps improve the appearance of
woven code that uses subscripts and/or superscripts heavily.  See -W[.