JPhrases/Hooks
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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