T and j are slow, but the tacit version is nice. 'A B'=:3|L:0(([:<i.)"1)3 5,:5 4 BA=: 600$A BB=: (5r3*600)$B ts=: 6!:2 , 7!:2@] ts 'P=:BA ;@:(((=&{: |.)"1 <@# (,}.)"1)"1 _) BB' 1.01695 1.65962e7 ts 'Q=:BA ;@:(((=&{: |.)"1 <@# (,"1}."1))"1 _) BB' 0.601724 1.65965e7 ts 'R=:BA ;@:(((=&{:"1 |."1) <@# (,}.)"1)"1 _) BB' 0.85174 1.65965e7 ts 'S=:BA ;@:(((=&{:"1 |."1) <@# (,"1}."1))"1 _) BB' 0.463207 1.65967e7 ts 'T=:; BA ([:<(=&{:)"1#(, }.)"1)"1 _ BB' 0.842222 1.6596e7 P-:T 1 f=: 13 :'x ;@:(((=&{: |.)"1 <@# (,}.)"1)"1 _) y' g=: 13 :'x;@:(((=&{: |.)"1 <@# (,"1}."1))"1 _) y' h=: 13 :'x ;@:(((=&{:"1 |."1) <@# (,}.)"1)"1 _) y' i=: 13 :'x ;@:(((=&{:"1 |."1) <@# (,"1}."1))"1 _) y' j=: 13 :';x([:<(=&{:)"1#(, }.)"1)"1 _ y' ts 'U=:BA j BB' 0.8406 1.6594e7 P-:U 1 f ;@:(((=&{: |.)"1 <@# (, }.)"1)"1 _) g ;@:(((=&{: |.)"1 <@# (,"1 }."1))"1 _) h ;@:(((=&{:"1 |."1) <@# (, }.)"1)"1 _) i ;@:(((=&{:"1 |."1) <@# (,"1 }."1))"1 _) j [: ; ([: < =&{:"1 # (, }.)"1)"1 _
-----Original Message----- From: programming-boun...@forums.jsoftware.com [mailto:programming-boun...@forums.jsoftware.com] On Behalf Of Aai Sent: Thursday, October 25, 2012 8:59 AM To: Programming forum Subject: [Jprogramming] Manipulating ranks (was: stitching matrices) Data from 'stitching matrices' 'A B'=:3|L:0(([:<i.)"1)3 5,:5 4 BA=. 600$A BB=. (5r3*600)$B Observe execution times ts 'P=.BA ;@:(((=&{: |.)"1 <@# (,}.)"1)"1 _) BB' 1.70547 1.6588e7 ts 'Q=.BA ;@:(((=&{: |.)"1 <@# (,"1}."1))"1 _) BB' 1.00185 1.65882e7 ts 'R=.BA ;@:(((=&{:"1 |."1) <@# (,}.)"1)"1 _) BB' 1.56342 1.65882e7 ts 'S=.BA ;@:(((=&{:"1 |."1) <@# (,"1}."1))"1 _) BB' 0.856076 1.65885e7 P is the desired result. P-:"2 Q,R,:S 1 1 1 -- Met vriendelijke groet, @@i = Arie Groeneveld ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm