Re: [Jprogramming] Matrix equation

2014-08-22 Thread Papp Erik Tamás
Your solutions of Wx and dX are perfect! Thank you, Erik - Eredeti levél (Original Message) - Feladó: Mike Day Dátum: Szerda, Augusztus 20, 2014 4:42 du Tárgy: Re: [Jprogramming] Matrix equation Címzett: programm...@jsoftware.com > 0. Your J expression for Wx looks wrong to me. &

Re: [Jprogramming] Matrix equation

2014-08-20 Thread Henry Rich
This might be a good use of dissect, to see the shapes and values all at once. http://www.jsoftware.com/jwiki/Vocabulary/Dissect Henry Rich On 8/20/2014 7:27 PM, Mike Day wrote: Raul's right of course. Although Wx is indeed a scalar, Nc and so NcI are 1x1 matrices. NcI acts like a scalar,

Re: [Jprogramming] Matrix equation

2014-08-20 Thread Mike Day
Raul's right of course. Although Wx is indeed a scalar, Nc and so NcI are 1x1 matrices. NcI acts like a scalar, but if we replace NcI by scalar nci (say), then CT mp NcI mp C may be replaced by CT mp nci * C , or CT mp C * nci , etc. Mike On 20/08/2014 15:42, Mike Day wrote: 0. Your J e

Re: [Jprogramming] Matrix equation

2014-08-20 Thread Raul Miller
On Wed, Aug 20, 2014 at 10:42 AM, Mike Day wrote: > 1. Nc = C.Nb.CT is scalar, and therefore NcI is also scalar. ... > Please note that scalar part-expressions could be moved around, and they may > be applied with a simple * verb. > I haven't done that here. Note that expressing these values as

Re: [Jprogramming] Matrix equation

2014-08-20 Thread Mike Day
0. Your J expression for Wx looks wrong to me. If you want to get Wx = (1-(q0^2)-(q1^2)-(q2^2)-(q3^2))%2 in conventional arithmetic notation then you need Wx=:(1-(q0^2)+(q1^2)+(q2^2)+(q3^2))%2 or Wx=:(1-+/*:q)%2 NB. Your J-expression is effectively (1- -/ *:q)%2 or [Wx=: -: -. +/

Re: [Jprogramming] Matrix equation

2014-08-20 Thread Papp Erik Tamás
Thanks for quick answer Erik - Eredeti levél (Original Message) - Feladó: Raul Miller Dátum: Szerda, Augusztus 20, 2014 11:27 de Tárgy: Re: [Jprogramming] Matrix equation Címzett: Programming forum > I think what you are asking about is: where do you put the > parenthesis?

Re: [Jprogramming] Matrix equation

2014-08-20 Thread Papp Erik Tamás
Thank you for your answer. Yes I try to write a J program for 3D similarity transformation. Erik Papp - Eredeti levél (Original Message) - Feladó: Henry Rich Dátum: Szerda, Augusztus 20, 2014 1:39 du Tárgy: Re: [Jprogramming] Matrix equation Címzett: programm...@jsoftware.com > I h

Re: [Jprogramming] Matrix equation

2014-08-20 Thread Henry Rich
I have no idea what this equation is trying to do, but the pattern NbI * (...) * NbI looks like it's trying to be a similarity transformation, but one of the outer matrices would need to be the inverse of the other. Just wondering, Henry Rich On 8/20/2014 5:24 AM, Raul Miller wrote: I thin

Re: [Jprogramming] Matrix equation

2014-08-20 Thread bill lam
IIRC matrix multiplication is non-associative, without parenthesis, J is post multiplication. Or I was wrong. On Aug 20, 2014 5:26 PM, "Raul Miller" wrote: > I think what you are asking about is: where do you put the parenthesis? > > That suggests: > > dX=: ((NbI-NbI mp CT mp NcI mp C mp NbI)m

Re: [Jprogramming] Matrix equation

2014-08-20 Thread Raul Miller
I think what you are asking about is: where do you put the parenthesis? That suggests: dX=: ((NbI-NbI mp CT mp NcI mp C mp NbI)mp W)+NbI mp CT mp NcI mp Wx In other words, you almost had it. Thanks, -- Raul On Wed, Aug 20, 2014 at 3:43 AM, "Papp Erik Tamás" wrote: > Dear Forum, > > Can s

[Jprogramming] Matrix equation

2014-08-20 Thread Papp Erik Tamás
Dear Forum, Can somebody help me to solve the folloving matrix equation? pps=:9!:11 NB. set print precision pps 20 mp=: +/ . * NB. Matrix product NB.=== NB. The following matrix e