# Less than or Equal to

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Main article: Comparison function
 ≤

Less than or Equal to () is a comparison function which tests whether the left argument is tolerantly less than or equal to the right argument, returning 1 if this is the case and 0 otherwise. It is the negation of Less than (<), and in fact was called Not greater in APL\360.

## Boolean function

When the arguments to Less than or Equal to are Boolean, it is the material implication Boolean function, also known as the IMPLY gate:

0 1
0 1 1
1 0 1

In the context of logic, it can be read as implies.

Less than or Equal to Scan is an occasionally used pattern related to Less than Scan. While <\ changes all 1s after the first to 0, \ changes all 0s after the first to 1. Thus \A ${\displaystyle \Leftrightarrow }$ ~<\~A.

\ 1 0 1 0 0 0 1 0
1 0 1 1 1 1 1 1

\ appears in the FinnAPL idiom library as entry 350, "Not first zero".