Lau: Restricting myself to the topic of function composition, I want to note that [: and @: have much the same meaning. For early learning use either and try switching if you trouble.
On 12/6/09, Lau B. Jensen <[email protected]> wrote: > With some great tips to help me along, Ive done as follows > > #5: Find a number evenly divsable with all ints from 1 - 20 > > *./ >:i.20 > > #6: Difference between Sum of the squares and square of the sum > (from the ints 1 - 100) > > This one really had me eating my words regarding combining functions for > a while. Until I > discovered [: cap, I struggled to make this simple algo run. I even > tried naming the components > to no avail. Eventually I ended up with > > (([:*:+/)-([:+/*:)) >:i.100 > > #7: Find the 10001.th prime > > p: <: 10001 > > #8: Find the greatest product of 5 consecutive numbers in a 1000-digit > number > > This was a bit disappointing for me, as I thought I could solve it > straight off, but quickly > ran into all sorts of trouble. > > I started out just working with a subset of the entire number > > data=: ": 73167176531330624919225119674426574742355349194934x > > With that as a string representation, I figured that partitioning it > would be simple > > 5<\ data > +-----+-----+-----+-----+-----+ > |73167|31671|16717|67176|71765|....... > +-----+-----+-----+-----+-----+ > > And it was. So all thats left is calculating the product of the > individual cells. > Which I had hoped was something like > > */\"0 (5<\ data) > > But for some reason that just adds a leading axis and does nothing to > the individual cells > > (*/\"0)"0 ,(5<\ data) > +-----+ > |73167| > +-----+ > |31671| > +-----+ > |16717| > +-----+ > |67176| > +-----+ > ... > > So my question might essentially be narrowed down to this: How do I > apply */ to the digits of > each window? > > Then just to follow up on Mr. Brons comment: I might be spoiled from my > Clojure experience, but > I find it very inhibiting to have strict evaluation as my only option. > Lazy evaluation is not some > small finnimbrun, but it effectively alters the way you model code. Is > this on the drawing board > for the next release of J, or has someone held to a > floccinaucinihilipilification of lazy-seqs ? > > Anyway, that made #9 more complex than it needed to be. Any comments > hints, criticisms etc of the code is > most welcomed. > > /Lau > ---------------------------------------------------------------------- > For information about J forums see http://www.jsoftware.com/forums.htm > ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
