Viktor,
What version of SBCL are you running, and what do you mean by "nonsense results"? When I run sbcl 1.0.18.debian, I get an error from (test 1000) which looks like it's in the printing routine as it tries to return the answer matrix: debugger invoked on a SB-SYS:MEMORY-FAULT-ERROR in thread #<THREAD "initial thread" RUNNING {10039ADBF1}>: Unhandled memory fault at #x0. Type HELP for debugger help, or (SB-EXT:QUIT) to exit from SBCL. restarts (invokable by number or by possibly-abbreviated name): 0: [ABORT] Exit debugger, returning to top level. (SB-SYS:MEMORY-FAULT-ERROR) 0] WARNING: Starting a select without a timeout while interrupts are disabled. :ba 0: (SB-SYS:MEMORY-FAULT-ERROR) 1: (SB-SYS:MEMORY-FAULT-ERROR)[:EXTERNAL] 2: ("foreign function: #x41EAA2") 3: ("foreign function: #x41EB70") 4: ("foreign function: #x40D53D") 5: ("foreign function: #x41CA5C") 6: (SB-KERNEL::COLLECT-GARBAGE 0) 7: ((FLET SB-THREAD::WITH-MUTEX-THUNK)) 8: ((FLET #:WITHOUT-INTERRUPTS-BODY-[CALL-WITH-MUTEX]477)) 9: ((FLET #:WITHOUT-INTERRUPTS-BODY-[SUB-GC]60)) 10: (SB-KERNEL:SUB-GC)[:EXTERNAL] 11: ("foreign function: #x41EAA2") 12: ("foreign function: #x40D435") 13: ("foreign function: #x4116C3") 14: (SB-BIGNUM:MULTIPLY-BIGNUM-AND-FIXNUM #<unavailable argument> #<unavailable argument>) 15: (SB-IMPL::FLONUM-TO-DIGITS 0.006426902231453881d0 #<unavailable argument> NIL) 16: (SB-IMPL::OUTPUT-FLOAT-AUX 0.006426902231453881d0 #<SB-PRETTY:PRETTY-STREAM {100631AE51}> -3 8) 17: (SB-PRETTY:OUTPUT-PRETTY-OBJECT 0.006426902231453881d0 #<SB-PRETTY:PRETTY-STREAM {100631AE51}>) 18: ((FLET #:WITH-PRETTY-STREAM-2825) #<SB-PRETTY:PRETTY-STREAM {100631AE51}>) 19: ((LABELS SB-PRETTY::OUTPUT-GUTS) #<SB-PRETTY:PRETTY-STREAM {100631AE51}> 0 (1000)) 20: ((FLET #:WITH-PRETTY-STREAM-2825) #<SB-PRETTY:PRETTY-STREAM {100631AE51}>) 21: ((LABELS SB-PRETTY::OUTPUT-GUTS) #<SB-PRETTY:PRETTY-STREAM {100631AE51}> 0 (1000 1000)) 22: (SB-PRETTY:OUTPUT-PRETTY-OBJECT #2A((-0.03152179146033235d0 -0.0064356015982750805d0 0.031318650821186636d0 0.021215786371980315d0 0.003314355400406193d0 0.0033404976598180773d0 -0.024914202255263d0 0.022145320720119623d0 -0.023703547290539858d0 0.010257175021330184d0 ... 23: (PRINC #2A((-0.03152179146033235d0 -0.0064356015982750805d0 0.031318650821186636d0 0.021215786371980315d0 0.003314355400406193d0 ...
I didn't try (test 3000). By the way, I tried Clozure CL 1.2 on the same platform (Debian amd64) with both (test 1000) and (test 3000), and both run to completion and look reasonable, so I think at least what I'm seeing is a problem with SBCL.
Liam
On Sun, Mar 8, 2009 at 8:11 AM, Viktor Leis viktor.leis@googlemail.com wrote:
Hi,
I've got a problem with singular value decomposition: Big matrices (e.g. 3000x3000) crash SBCL. With a matrix of 1000x1000 it doesn't crash but instead I usually get nonsense results. With a small matrix (e.g. 500x500) it works perfectly fine. I get the same behavior on 32 and 64 bit Linux.
(defun test (n) (let ((a (make-marray 'double-float :dimensions (list n n))) (s (make-marray 'double-float :dimensions n)) (v (make-marray 'double-float :dimensions (list n n)))) (dotimes (i n) (dotimes (j n) (setf (maref a i j) (random 1.0d0)))) (multiple-value-list (sv-decomposition a s v))))
Viktor Leis