Not Equal to (≠
) is a comparison function which tests whether argument elements are tolerantly^{[1]} unequal. It is the negation of Equal to (=
). Thus it returns 0 if the elements being compared match and 1 if they do not.
Examples
See Equal to for a more detailed treatment of equality testing.
2 2.5 3 3.5 ≠ 2.5
1 0 1 1
Boolean function
When the arguments to Not Equal to are Boolean, it is the exclusive or or xor function:
Xor is one of the most important Boolean functions because it is equivalent to addition of the arguments with modulus 2. Like addition, it is commutative and associative. It is also equivalent to subtraction with modulus 2 because the 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 v
is a Boolean vector then ≠/v
$\Leftrightarrow$ 2+/v
.
External links
Documentation
References
APL builtins [edit]

Primitives (Timeline) 
Functions

Scalar

Monadic

Conjugate ∙ Negate ∙ Signum ∙ Reciprocal ∙ Magnitude ∙ Exponential ∙ Natural Logarithm ∙ Floor ∙ Ceiling ∙ Factorial ∙ Not ∙ Pi Times ∙ Roll ∙ Type ∙ Imaginary ∙ Square Root ∙ Round

Dyadic

Add ∙ Subtract ∙ Times ∙ Divide ∙ Residue ∙ Power ∙ Logarithm ∙ Minimum ∙ Maximum ∙ Binomial ∙ Comparison functions ∙ Boolean functions (And, Or, Nand, Nor) ∙ GCD ∙ LCM ∙ Circular ∙ Complex ∙ Root

NonScalar

Structural

Shape ∙ Reshape ∙ Tally ∙ Depth ∙ Ravel ∙ Enlist ∙ Table ∙ Catenate ∙ Reverse ∙ Rotate ∙ Transpose ∙ Raze ∙ Mix ∙ Split ∙ Enclose ∙ Nest ∙ Cut (K) ∙ Pair ∙ Link ∙ Partitioned Enclose ∙ Partition

Selection

First ∙ Pick ∙ Take ∙ Drop ∙ Unique ∙ Identity ∙ Stop ∙ Select ∙ Replicate ∙ Expand ∙ Set functions (Intersection ∙ Union ∙ Without) ∙ Bracket indexing ∙ Index ∙ Cartesian Product ∙ Sort

Selector

Index generator ∙ Grade ∙ Index Of ∙ Interval Index ∙ Indices ∙ Deal ∙ Prefix and suffix vectors

Computational

Match ∙ Not Match ∙ Membership ∙ Find ∙ Nub Sieve ∙ Encode ∙ Decode ∙ Matrix Inverse ∙ Matrix Divide ∙ Format ∙ Execute ∙ Materialise ∙ Range

Operators 
Monadic

Each ∙ Commute ∙ Constant ∙ Replicate ∙ Expand ∙ Reduce ∙ Windowed Reduce ∙ Scan ∙ Outer Product ∙ Key ∙ IBeam ∙ Spawn ∙ Function axis ∙ Identity (Null, Ident)

Dyadic

Bind ∙ Compositions (Compose, Reverse Compose, Beside, Withe, Atop, Over) ∙ Inner Product ∙ Determinant ∙ Power ∙ At ∙ Under ∙ Rank ∙ Depth ∙ Variant ∙ Stencil ∙ Cut ∙ Direct definition (operator) ∙ Identity (Lev, Dex)

Quad names

Index origin ∙ Comparison tolerance ∙ Migration level ∙ Atomic vector
