Dan Baronet: Difference between revisions

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'''Daniel Baronet''' (6 May 1956–1 Nov 2016), also known as '''APLtrainer''', was an APL (and later [[J]]) programmer since 1976, working for [[I.P. Sharp Associates]] in Melbourne, Toronto, Montreal, and Copenhagen, from 1983 to 1988, and for [[Dyalog Ltd]] from 2006 until his death.
'''Daniel Baronet''' (6 May 1956–1 Nov 2016), also known as '''APLtrainer''', was an APL (and later [[J]]) programmer since 1976, working for [[I.P. Sharp Associates]] in Melbourne, Toronto, Montreal, and Copenhagen, from 1983 to 1988, and for [[Dyalog Ltd]] from 2006 until his death.


While Baronet was responsible for Dyalog's ''Simple APL Library Toolkit'' (SALT) and its framework for [[user command]]s (affectionately known as ''spice''), but also worked on many other APL tools through his company Milinta Inc, specialising in the development of free open-source tools to transfer of APL code between dialects.<ref>Rick Procter. [http://www.aplborealis.com/danb2016.html Obituary for Daniel Baronet]. APL Borealis.</ref> He was a prolific writer and presented at many events.
Baronet was responsible for Dyalog's ''Simple APL Library Toolkit'' (SALT) and its framework for [[user command]]s (affectionately known as ''spice''), but also worked on many other APL tools through his company Milinta Inc, specialising in the development of free open-source tools to transfer of APL code between dialects.<ref>Rick Procter. [http://www.aplborealis.com/danb2016.html Obituary for Daniel Baronet]. APL Borealis.</ref> He was a prolific writer and presented at many events.


== The "Dan Baronet special" ==
== The "Dan Baronet special" ==
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Baronet was famous for innovative uses of APL primitives. He's credited with discovering that <source lang=APL inline>b⊥b</source> or, as he preferred writing it, <source lang=APL inline>⊥⍨b</source>, counts the number of trailing ones in the Boolean vector <source lang=APL inline>b</source>:<ref>Roger Hui. [http://danielbaronet.rip/ Tribute to Daniel Baronet]. DanielBaronet.RIP</ref>
Baronet was famous for innovative uses of APL primitives. He's credited with discovering that <source lang=APL inline>b⊥b</source> or, as he preferred writing it, <source lang=APL inline>⊥⍨b</source>, counts the number of trailing ones in the Boolean vector <source lang=APL inline>b</source>:<ref>Roger Hui. [http://danielbaronet.rip/ Tribute to Daniel Baronet]. DanielBaronet.RIP</ref>


<source lang=apl inline>⊥</source> ([[Decode]]) performs base conversion. If the left argument is a vector, it performs *mixed* base conversion.
<source lang=apl inline>⊥</source> ([[Decode]]) performs base conversion. If the left argument is a vector, it performs ''mixed'' base conversion.


For a base vector <math>b = b_n,\cdots,b_0</math> and a digit vector <math>a = a_n,\cdots, a_0</math>, <source lang=apl inline>b ⊥ a</source> converts <math>a</math> to the mixed base <math>b</math>, i.e., it computes <math>b_0\cdots b_{n-1}a_n + \cdots + b_0b_1a_2 + b_0a_1 + a_0</math>.
For a base vector <math>b = b_n,\cdots,b_0</math> and a digit vector <math>a = a_n,\cdots, a_0</math>, <source lang=apl inline>b ⊥ a</source> converts <math>a</math> to the mixed base <math>b</math>, i.e., it computes <math>b_0\cdots b_{n-1}a_n + \cdots + b_0b_1a_2 + b_0a_1 + a_0</math>.

Revision as of 14:19, 20 November 2020

Daniel Baronet (far left) at IPSA50 reunion

Daniel Baronet (6 May 1956–1 Nov 2016), also known as APLtrainer, was an APL (and later J) programmer since 1976, working for I.P. Sharp Associates in Melbourne, Toronto, Montreal, and Copenhagen, from 1983 to 1988, and for Dyalog Ltd from 2006 until his death.

Baronet was responsible for Dyalog's Simple APL Library Toolkit (SALT) and its framework for user commands (affectionately known as spice), but also worked on many other APL tools through his company Milinta Inc, specialising in the development of free open-source tools to transfer of APL code between dialects.[1] He was a prolific writer and presented at many events.

The "Dan Baronet special"

Baronet was famous for innovative uses of APL primitives. He's credited with discovering that b⊥b or, as he preferred writing it, ⊥⍨b, counts the number of trailing ones in the Boolean vector b:[2]

(Decode) performs base conversion. If the left argument is a vector, it performs mixed base conversion.

For a base vector and a digit vector , b ⊥ a converts to the mixed base , i.e., it computes .

Now, in a monadic context, (Commute) causes the function to the left to be called with equal left and right arguments.

So ⊥⍨b is defined as b⊥b, which computes , the sum of all cumulative products from the right to the left.

For k trailing ones, the k rightmost products are 1 and all others are 0, so their sum is equal to k.[3]

Publications

APL conferences

Dyalog user meetings

References

  1. Rick Procter. Obituary for Daniel Baronet. APL Borealis.
  2. Roger Hui. Tribute to Daniel Baronet. DanielBaronet.RIP
  3. Stack User "Dennis". Answer in Dyalog APL to Adám Brudzewsky's code golf challenge. Code Golf and Coding Challenges Stack Exchange.
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