Less than

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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 (<syntaxhighlight lang=apl inline>≥</source>). 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:

<syntaxhighlight lang=apl inline><</source> <syntaxhighlight lang=apl inline>0</source> <syntaxhighlight lang=apl inline>1</source>
<syntaxhighlight lang=apl inline>0</source> <syntaxhighlight lang=apl inline>0</source> <syntaxhighlight lang=apl inline>1</source>
<syntaxhighlight lang=apl inline>1</source> <syntaxhighlight lang=apl inline>0</source> <syntaxhighlight lang=apl inline>0</source>

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: <syntaxhighlight lang=apl> 

     <\ 0 0 1 0 0 0 1 0

0 0 1 0 0 0 0 0 </source> 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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