Problem: fibn vector_length_100thousand runs too long (10 hours and running). 35% of my memory & all swap is available.
The analysis shown indicates the problem could run in well under an hour. Did memoize decide the task is impossible? Discarding the M. cache every now and then might help. References: ProjectEuler #304, Dijkstra's Fibonacci formula http://www.maths.surrey.ac.uk/hosted-sites/R.Knott/Fibonacci/fibFormula.html#exact Thanks, Dave. $ jconsole NB. Least significant figures of large Fibonacci numbers. (9!:12 ,&(' '&,@":) 9!:14)'' NB. unix j7 5 j701/2011-01-10/11:25 ts=: 6!:2, 7!:2@] int =: = <. fibn_test =: +:@(<&2) + 2&| (,. fibn_test)i.6 0 2 1 3 2 0 3 1 4 0 5 1 fibn_even_term =: fibn@-: * +:@fibn@<:@-: + fibn@-: fibn_odd_term =: (fibn@<: +&*: fibn)@-:@>: fibn =: (1234567891011x | fibn_even_term`fibn_odd_term`0:`1:@.fibn_test)M."0 a=: 1!:1<'e304.primes' #primes=:".' '(I.LF=a)}a 100000 q: primes{~5?#primes 100000001643887 100000000146283 100000003087511 100000000129571 100000000933793 NB.-------------------KEY TIMING RESULT-------------------- ts'fibn 10{.primes' NB. could take well under an hour all 0.003889 142592 fibn i.10 NB. fibn is possibly correct 0 1 1 2 3 5 8 13 21 34 NB. without M. fibn=:(1234567891011x | fibn_even_term`fibn_odd_term`0:`1:@.fibn_test)"0 ts'fibn {.primes' longer than I'll wait. ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
