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
~<\~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".
External links
Documentation
APL builtins [edit]  

Primitive functions  
Scalar  
Monadic  Conjugate ∙ Negate ∙ Signum ∙ Not ∙ Roll ∙ Type  
Dyadic  Add ∙ Subtract ∙ Equal to (Xnor) ∙ Not Equal to (Xor) ∙ Minimum ∙ Maximum ∙ Comparison functions  
NonScalar  
Structural  Shape ∙ Reshape ∙ Tally ∙ Depth ∙ Ravel ∙ Reverse ∙ Raze ∙ Mix ∙ Cut (K) ∙ Pair ∙ Replicate ∙ Partitioned Enclose  
Selection  Take ∙ Drop ∙ Unique ∙ Identity ∙ Select  
Selector  Index generator ∙ Interval Index ∙ Indices  
Computational  Match ∙ Not Match ∙ Nub Sieve ∙ Format ∙ Execute  
Primitive operators  Monadic  Each ∙ Replicate  
Dyadic  Reverse Compose  
Quad names  
Arrays  Index origin ∙ Migration level  
Functions  
Operators  
Other  Zilde ∙ High minus ∙ Function axis 