128!:0 underlies %. and %. rejects singular matrices. http://www.jsoftware.com/jwiki/Essays/QR_Decomposition presents a close model of 128!:0 . What modifications to the verb QR are needed so that it works on singular matrices?
----- Original Message ----- From: John Randall <[EMAIL PROTECTED]> Date: Monday, August 27, 2007 6:44 Subject: [Jprogramming] QR reduction To: [email protected] > Is there some reason why 128!:0 only works on nonsingular matrices? > > For example > > 128!:0 > 0 0; 1 1 > |domain error > | 128!:0>0 0;1 1 > > However > > 'q r'=: (2 2$ 0 _1 _1 0);2 2 $ _1 _1 0 0 > > seems a perfectly good QR reduction. > > q (+/ .*) r > 0 0 > 1 1 ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
