[Jprogramming] index origin 0

Mon Jul 26 23:04:55 HKT 2010

 I studied electrical engineering, but graduated with a BS in 
philosophy of science followed by an MS in photographic science. I used 
APL for statistical computing of colorimetric data in two standards 
laboratories. Later I used APL for digitizing an old Hardy 
spectrophotometer and doing off-line digital signal processing on the 
data for wavelength calibration. Still later, I supported a time-series 
database for oil traders. I have done a little programming in J, and 
with the help of this forum actually made a some money using J software 
to warp infra-red images.
In my APL work, only occasionally did I use an index origin of zero. It 
just seemed more intuitive to use the APL default index origin of one. 
That may be counter-intuitive to someone else. The ability to make the 
index origin a local variable allowed functions to be written either way 
without regard to the larger program, except the added complexity of 
changing index origins in the code. This made the re-use (stealing) of 
code written with the "wrong" index origin relatively easy.
The choice of the index origin shares some problems with the choice of 
standards. Ultimately, the choice is arbitrary, but should not be 
capricious. Either index origin satisfies the arbitrary condition, and 
neither seems to be capricious. Use of one may provide a sense of 
elegance in a particular situation that the other does not, but this is 
dependent on the situation.
In my opinion, the elegance of J, though frustrating to learn, far 
surpasses any loss of elegance from not being able to choose an index 
origin. The fixed index origin automatically facilitates the re-use of 
code. That said, I do miss the ability to choose. Having the index 
origin set to zero is not a great loss, but it did add one more 
annoyance to learning the language. Maybe the only ones who might care 
are the ones who once used APL and only those who used an index origin 
of one.
Very happy with J, if I could ever get really good at it,
David Porter