The unit matrix is =/~i.5 1 0 0 0 0 0 1 0 0 0 0 0 1 0 0 0 0 0 1 0 0 0 0 0 1
- Bo >________________________________ > Fra: Don & Cathy Kelly <[email protected]> >Til: [email protected] >Sendt: 0:47 tirsdag den 20. november 2012 >Emne: Re: [Jprogramming] Verb definition + inadvertent train formation. > >No - I should have made it clear that the actual y is a list of n >numbers and I need to add this list to the diagonal of a matrix. >Since this will (of necessity) be within a loop and each time both the >list and matrix will be modified (except for size), >I have come to the conclusion that I should make a single unit matrix >outside the iteration and use this each time. > ] u=:=@i.@#i.5 > >1 0 0 0 0 >0 1 0 0 0 >0 0 1 0 0 >0 0 0 1 0 >0 0 0 0 1 > >y=: 2 3 5 4 10 > > ]u *y >2 0 0 0 0 >0 3 0 0 0 >0 0 5 0 0 >0 0 0 4 0 >0 0 0 0 10 >repeating with different y values as needed. > >The algorithm for u is taken from the "phrases" section of the >vocabulary-maybe you have a simpler one?- >Thanks > >Don > > >On 18/11/2012 10:33 PM, bob therriault wrote: >> Hi Don, >> >> Are you looking for >> >> y=:5 >> c=:(*=)&i. >> c y >> 0 0 0 0 0 >> 0 1 0 0 0 >> 0 0 2 0 0 >> 0 0 0 3 0 >> 0 0 0 0 4 > >> Cheers, bob >> >> On 2012-11-18, at 7:13 PM, Don & Cathy Kelly wrote: >> >>> OOPs' I meant y=:i.5 5 >>> >>> Don >>> On 18/11/2012 7:04 PM, Don & Cathy Kelly wrote: >>>> That gives the diagonal nicely but the problem that I didn't express >>>> clearly is that I want a matrix as follows >>>> y=:i.5 >>>> >>>> ]result =: (* =@i.@#) y >>>> 0 0 0 0 0 >>>> 0 1 0 0 0 >>>> 0 0 2 0 0 >>>> 0 0 0 3 0 >>>> 0 0 0 0 4 >>>> which II can get by >>>> c=:* =@i.@# >>>> c y >>>> 0 0 0 0 0 >>>> 0 1 0 0 0 >>>> 0 0 2 0 0 >>>> 0 0 0 3 0 >>>> 0 0 0 0 4 >>>> >>>> For my purposes I can use a base nth order unit matrix by the phrase as >>>> given in phrases as m=:=@i.@# y >>>> and then deal with m* y1 , m* y2 etc which suits my purpose which is to >>>> form a specific Jacobean used for power system load flows. >>>> I have handled this problem in APL and am trying to replicate the coding >>>> more directly in J-mainly as an exploration of J for my own satisfaction. >>>> >>>> Thank you >>>> >>>> Don Kelly >> ---------------------------------------------------------------------- >> For information about J forums see http://www.jsoftware.com/forums.htm >> > >---------------------------------------------------------------------- >For information about J forums see http://www.jsoftware.com/forums.htm > > > ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
