Less than: Difference between revisions

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* [https://help.dyalog.com/latest/index.htm#Language/Primitive%20Functions/Less.htm Dyalog]
* [https://help.dyalog.com/latest/index.htm#Language/Primitive%20Functions/Less.htm Dyalog]
* [http://microapl.com/apl_help/ch_020_020_290.htm APLX]
* [http://microapl.com/apl_help/ch_020_020_290.htm APLX]
* [https://mlochbaum.github.io/BQN/doc/arithmetic.html#comparisons BQN]
* J [http://www.jsoftware.com/help/dictionary/d010.htm Dictionary], [https://code.jsoftware.com/wiki/Vocabulary/lt#dyadic NuVoc]
* J [http://www.jsoftware.com/help/dictionary/d010.htm Dictionary], [https://code.jsoftware.com/wiki/Vocabulary/lt#dyadic NuVoc]


Revision as of 02:21, 28 May 2022

Main article: Comparison function
For the set function, see Without.
<

Less than (<) is a comparison function which tests whether the left argument is tolerantly less than and not equal to the right argument, returning 1 if this is the case and 0 otherwise. It is the negation of Greater than or Equal to (≥). Less-than Scan, which leaves only the first 1 in a Boolean vector set[1], is a notable pattern.

Boolean function

When the arguments to Less than are Boolean, it is the converse nonimplication Boolean function:

< 0 1
0 0 1
1 0 0

It returns 1 only if the left argument is 0 and the right argument is 1, and is identical to Residue. Considered as a logical operation, it can be read as isn't, as opposed to.

Less-than Scan on a Boolean vector returns a vector which indicates the position of the first 1 in the argument, if any: 

      <\ 0 0 1 0 0 0 1 0
0 0 1 0 0 0 0 0

It is idiom 348, "First one", in the FinnAPL idiom library.

External links

Documentation

References

  1. ↑ Last, Phil. "Boolean Reductions". Vector Journal volume 26, number 1. 2013-09.
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