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2F. Hooks

A pair of functions in isolation form a hook whose monadic case is defined as in:

(= <.) y is equivalent to y = <. y

hence the function h=: =<. compares its argument with its integer part, and therefore provides a test for integers. Hooks occur frequently in most sections.

 m0=: It=: =<. Integer test m1=: Rt=: =+ Real test d2=: \$,: x copies of y d3=: \$, Reshape as in APL m4=: cf=: (+%)/ Continued fraction m5=: cfc=: (+%)/\ Continued fraction convergents m6=: ifb=: # i.@# Integers from boolean list m7=: [m ([m)y invokes m y , then returns y

For example:

```   cf 3 7 15 1		NB. Approximation to pi
3.14159

cfc 3 7 15 1		NB. Convergents to pi
3 3.14286 3.14151 3.14159

cfc 1 1 1 1 1 1 1	NB. Convergents to golden mean
1 2 1.5 1.66667 1.6 1.625 1.61538

cfc 10\$1x		NB. As above in extended precision
1 2 3r2 5r3 8r5 13r8 21r13 34r21 55r34 89r55```

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