Yes this is really strange: I thought operations with MMF nouns should not take up physical memory. Especially if the result is mapped, moreover if there are no intermediate operations.
But even simple operations, like C=: A*B all mapped take even more memory than not mapped. (Using left arg "JFL map_jmf_ y" does not help.) Example 1. require 'jmf files dir' ]P=: jpath'~temp' c:\math\j601\temp A=: i.20 20 B=: %>:i.-20 20 createjmf_jmf_ (P,'/A.jmf');*/20 20 8 createjmf_jmf_ (P,'/B.jmf');*/20 20 8 createjmf_jmf_ (P,'/C.jmf');*/20 20 8 map_jmf_ 'A1';P,'/A.jmf' map_jmf_ 'B1';P,'/B.jmf' map_jmf_ 'C1';P,'/C.jmf' A1=: i.20 20 B1=: %>:i.-20 20 7!:2 'A * B' 4800 7!:2 'C1=: A1 * B1' 4992 Example 2. (Choose total sizes exceeding your physical + swap file, swap file should be fixed). createjmf_jmf_ (P,'/a.jmf'); 40e6 * 8 createjmf_jmf_ (P,'/b.jmf'); 40e6 * 8 createjmf_jmf_ (P,'/c.jmf'); 40e6 * 8 map_jmf_ 'A';P,'/a.jmf' map_jmf_ 'B';P,'/b.jmf' map_jmf_ 'C';P,'/c.jmf' showmap_jmf_'' +-------+-----------------------+--+---+---+----------+----------+--+---------+----+ |name |fn |sn|fh |mh |address |header |ts|msize |refs| +-------+-----------------------+--+---+---+----------+----------+--+---------+----+ |A_base_|c:\math\j601\temp/a.jmf| |224|228|539820032 |539820032 | |320000000|2 | +-------+-----------------------+--+---+---+----------+----------+--+---------+----+ |B_base_|c:\math\j601\temp/b.jmf| |232|236|859832320 |859832320 | |320000000|2 | +-------+-----------------------+--+---+---+----------+----------+--+---------+----+ |C_base_|c:\math\j601\temp/c.jmf| |240|244|1179844608|1179844608| |320000000|2 | +-------+-----------------------+--+---+---+----------+----------+--+---------+----+ A=: i.40e6 B=: i.40e6 B=: >:B B=: %B |out of memory | B=: %B unmapall_jmf_'' NB. OK let's restart 0 0 0 map_jmf_ 'B';P,'/b.jmf' B=: %B unmapall_jmf_'' 0 map_jmf_ 'C';P,'/c.jmf' C=: 40e6#0.1 NB. initialize to form of results unmapall_jmf_'' 0 0 0 map_jmf_ 'A';P,'/a.jmf' map_jmf_ 'B';P,'/b.jmf' map_jmf_ 'C';P,'/c.jmf' C=: A*B |out of memory | C=:A *B dir P 1.ijs 417 23-Apr-06 16:25:24 1.ijx 4509 07-May-06 03:38:21 2.ijs 1050 27-Apr-06 06:39:33 a.jmf 320000284 07-May-06 03:40:21 b.jmf 320000284 07-May-06 03:40:24 c.jmf 320000284 07-May-06 03:40:27 temp.txt 111 22-Apr-06 08:19:34 --- Anssi Seppälä <[EMAIL PROTECTED]> wrote: > I have two big 2-dimensional arrays in mapped files A and B. I need > to calculate +/ A * B efficiently and without "out of memory". > > In the case A was a vector the . (dot) can make it +/ . * , but this > does not work if A is a matrix. Is there a way to do this without a > program loop? > > Anssi __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
