You might find these verbs of some use. I cobbled them
together from some source which I should acknowledge,
but forget right now and it's late!
NB. Somewhat more exact than working on %:y as the input.
NB. convergents of continued fraction for %: y
rtn =: 3 : 0
y rtn y
:
'h t' =: ({.;}.) myroot y NB. continued fraction for %:y
y =. h, t$~ x.-1
ab =. ,r =. 1 2$1,~{. y
a0b0 =. 1 0
for_yi. }. y do.
nab =. x: a0b0 + yi * ab
r =. r,ab =. nab [ a0b0 =. ab
end.
r
)
NB. continued fraction elements for %: y
myroot =: 3 : 0
if. (=<.&.%:) y do. %:y return. end.
a =. e =. a0=. <.k=. %:k2=. y
k21 =. k2, n=.b=.1
end =. 0
while. end = 0 do.
d =. -/k21 * *:b,e
'd b e'=. (% | @:+./) d,'b e'=. n * b,e NB. reduce
a =. a, a0 =. <. d %~ e + b * k
end =. 1 = n =. d
e =. e -~ d * a0
end.
a
)
myroot 7
2 1 1 1 4
rtn 7
2 1
3 1
5 2
8 3
37 14
45 17
82 31
Mike
----------------------------------------------------------------------
For information about J forums see http://www.jsoftware.com/forums.htm
