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 Self-Classify =  _ 0 0 Equal

 =y classifies the items of the nub of y (that is, ~.y) according to equality with the items of y , producing a boolean table of shape #~.y by #y . For example: ``` y=: 3 3 \$ 'abcdef' y ; (~.y) ; (=y) +---+---+-----+ |abc|abc|1 0 1| |def|def|0 1 0| |abc| | | +---+---+-----+ ``` x=y is 1 if x is equal to y , and is otherwise 0 . If x or y is a finite floating-point or complex number, the comparison is made with a tolerance t , normally 2 to the power _44 but also controlled by the fit conjunction !. , as in x=!.0 y . Formally, x=y is 1 if the magnitude of x-y does not exceed t times the larger of the magnitudes of x and y . Tolerance applies similarly to other verbs as indicated for each, notably to Match (-:), to Floor (<.), and to Signum (*), but not to Grade (/:).

Both the monadic and dyadic cases of the verb = apply to nouns of any rank, and to boxed as well as simple nouns. For example:
```   ]a=: ;: 'Try and try and try again.'
+---+---+---+---+---+------+
|Try|and|try|and|try|again.|
+---+---+---+---+---+------+

~. a
+---+---+---+------+
|Try|and|try|again.|
+---+---+---+------+

=a
1 0 0 0 0 0
0 1 0 1 0 0
0 0 1 0 1 0
0 0 0 0 0 1

a = <'and'
0 1 0 1 0 0
```
Because of the limited precision of the computer, results which should agree (such as 144*(13%144) and 13) may not; the tolerant comparison allows such a comparison to show agreement (a result 1). More or less stringent comparisons may be made by using the conjunction !. to specify a tolerance t , as in the function eq=: =!.t .

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