Fdot


f.
Improved 		initial writing: 2003-07-14
last updated: 2004-10-26


f. has been improved so that v f. would exploit
the special code that would be exploited by a completely primitive version of v ;
the execution of x v f. y (and v f. y) would
be as fast and as lean as a completely primitive version of v . For example:

   ts=: 6!:2 , 7!:2@]   NB. time and space
   tally =: #
   rev=: |.
   x=: 100000 $ i. 6
   y=: i. 100000 10
   ts 'Expression'
Expression    J 5.03    J 5.02    Ratio
x #/. y   0.0114327   1.57370e6   0.0114442   1.57370e6
x tally/. y   0.114467 1.32402e7   0.115316 1.32402e7
x tally/.f. y   0.0117163 1.57414e6   0.0763963 6.94848e6   6.52 4.41
|."1 y   0.0383105 4.19520e6   0.0383065 4.19520e6
rev"1 y   0.193694 4.19578e6   0.183509 4.19578e6
rev"1 f. y   0.0380708 4.19558e6   0.0994439 4.19603e6   2.61 1.00