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{{Built-in|Not Equal to|<nowiki>≠</nowiki>}} is a [[comparison function]] which tests whether argument elements are [[Tolerant comparison|tolerantly]] unequal. It is the [[Not|negation]] of [[Equal to]] (<source lang=apl inline>=</source>). Thus it returns 0 if the [[element]]s being compared [[match]] and 1 if they do not.
{{Built-in|Not Equal to|<nowiki>≠</nowiki>}} is a [[comparison function]] which tests whether argument elements are [[Tolerant comparison|tolerantly]] unequal. It is the [[Not|negation]] of [[Equal to]] (<syntaxhighlight lang=apl inline>=</syntaxhighlight>). Thus it returns 0 if the [[element]]s being compared [[match]] and 1 if they do not.


== Examples ==
== Examples ==


See [[Equal to]] for a more detailed treatment of equality testing.
See [[Equal to]] for a more detailed treatment of equality testing.
<source lang=apl>
<syntaxhighlight lang=apl>
       2 2.5 3 3.5 ≠ 2.5
       2 2.5 3 3.5 ≠ 2.5
1 0 1 1
1 0 1 1
</source>
</syntaxhighlight>


== Boolean function ==
== Boolean function ==
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When the arguments to Not Equal to are [[Boolean]], it is the [[wikipedia:exclusive or|exclusive or]] or xor function:
When the arguments to Not Equal to are [[Boolean]], it is the [[wikipedia:exclusive or|exclusive or]] or xor function:
{|class=wikitable
{|class=wikitable
!<source lang=apl inline>≠</source>!!<source lang=apl inline>0</source>!!<source lang=apl inline>1</source>
!<syntaxhighlight lang=apl inline>≠</syntaxhighlight>!!<syntaxhighlight lang=apl inline>0</syntaxhighlight>!!<syntaxhighlight lang=apl inline>1</syntaxhighlight>
|-
|-
!<source lang=apl inline>0</source>
!<syntaxhighlight lang=apl inline>0</syntaxhighlight>
|<source lang=apl inline>0</source>||<source lang=apl inline>1</source>
|<syntaxhighlight lang=apl inline>0</syntaxhighlight>||<syntaxhighlight lang=apl inline>1</syntaxhighlight>
|-
|-
!<source lang=apl inline>1</source>
!<syntaxhighlight lang=apl inline>1</syntaxhighlight>
|<source lang=apl inline>1</source>||<source lang=apl inline>0</source>
|<syntaxhighlight lang=apl inline>1</syntaxhighlight>||<syntaxhighlight lang=apl inline>0</syntaxhighlight>
|}
|}
Xor is one of the most important [[Boolean function]]s because it is equivalent to [[addition]] of the arguments with [[modulus]] 2. Like addition, it is [[wikipedia:Commutative property|commutative]] and [[wikipedia:Associative property|associative]]. It is also equivalent to [[subtraction]] with modulus 2 because the [[Minus|negative]] of a number is the same as the original number (mod 2): the negative of an odd number is still odd, and the negative of an even number is still even.
Xor is one of the most important [[Boolean function]]s because it is equivalent to [[addition]] of the arguments with [[modulus]] 2. Like addition, it is [[wikipedia:Commutative property|commutative]] and [[wikipedia:Associative property|associative]]. It is also equivalent to [[subtraction]] with modulus 2 because the [[Minus|negative]] of a number is the same as the original number (mod 2): the negative of an odd number is still odd, and the negative of an even number is still even.


[[Reduction]] of a Boolean [[vector]] using Not Equal to yields 1 if there were an odd number of 1s in the argument and 0 otherwise. In APL, if <source lang=apl inline>v</source> is a Boolean vector then <source lang=apl inline>≠/v</source> {{←→}} <source lang=apl inline>2|+/v</source>.
[[Reduction]] of a Boolean [[vector]] using Not Equal to yields 1 if there were an odd number of 1s in the argument and 0 otherwise. In APL, if <syntaxhighlight lang=apl inline>v</syntaxhighlight> is a Boolean vector then <syntaxhighlight lang=apl inline>≠/v</syntaxhighlight> {{←→}} <syntaxhighlight lang=apl inline>2|+/v</syntaxhighlight>.


== External links ==
== External links ==
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=== Documentation ===
=== Documentation ===


* [http://help.dyalog.com/latest/index.htm#Language/Primitive%20Functions/Not%20Equal.htm Dyalog]
* [https://help.dyalog.com/latest/index.htm#Language/Primitive%20Functions/Not%20Equal.htm Dyalog]
* [http://microapl.com/apl_help/ch_020_020_340.htm APLX]
* [http://microapl.com/apl_help/ch_020_020_340.htm APLX]
* J [http://www.jsoftware.com/help/dictionary/d222.htm Dictionary], [https://code.jsoftware.com/wiki/Vocabulary/tildeco#dyadic NuVoc]
* J [http://www.jsoftware.com/help/dictionary/d222.htm Dictionary], [https://code.jsoftware.com/wiki/Vocabulary/tildeco#dyadic NuVoc]
* [https://mlochbaum.github.io/BQN/doc/arithmetic.html#comparisons BQN]


{{APL built-ins}}[[Category:Primitive functions]][[Category:Scalar dyadic functions]]
{{APL built-ins}}[[Category:Primitive functions]][[Category:Comparison functions]]

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