What you need to keep straight is the rank of the various parts. Breaking this into two parts, first evaluating the values for each value of x against the powers of x times the coefficients for each power:
x=:5 8 1 _1 1*"1 x^/i.3 1 _5 25 1 _8 64 Then sum each row. Here you have to override the rank of the sum: +/"1]1 _1 1*"1 x^/i.3 21 57 But you might prefer using p. which is much cleaner. 1 _1 1 p. x 21 57 On Thu, Aug 19, 2010 at 5:02 PM, Johann Hibschman <[email protected]<jhibschman%[email protected]> > wrote: > (I accidentally sent this to j.general, to which I'm not yet subscribed; > I don't expect that to go through, but if it does, apologies for the > duplication.) > > > Here's a simple question from a rank beginner: > > Expressing polynomials as, for example, > > +/1 _1 1*x^i.3 > > works well, as long as x is a scalar. If x is of higher rank, this > stops working. My somewhat brute-force solution is to manually set the > rank used, as in: > > x=:2 3 5 > +/1 _1 1*x^_ 0 i. 3 > > Is this good style? Is there a better way? > > Thanks, and pardon the pun, > Johann > > ---------------------------------------------------------------------- > For information about J forums see http://www.jsoftware.com/forums.htm > ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
