wrong LU decomposition
miro simko
miro_simko at hotmail.com
Mon Feb 4 19:10:02 CST 2008
--------
Bug report for Octave 2.1.73 configured for i486-pc-linux-gnu
Description:
-----------
octave computes wrong LU decomposition for given matrix A
correct decomposition A=L*U:
(1 2 3 4) (1 0 0 0) (1 2 3 4)
(2 9 12 15) = (2 1 0 0) * (0 5 6 7)
(3 26 41 49) (3 4 1 0) (0 0 8 9)
(5 40 107 135) (5 6 7 1) (0 0 0 10)
octave gives:
L= (0.20000 0.85714 -0.25000 1.00000)
(0.40000 1.00000 0.00000 0.00000)
(0.60000 -0.28571 1.00000 0.00000)
(1.00000 0.00000 0.00000 0.00000)
U=(5.00000 40.00000 107.00000 135.00000)
(0.00000 -7.00000 -30.80000 -39.00000)
(0.00000 0.00000 -32.00000 -43.14286)
(0.00000 0.00000 0.00000 -0.35714)
Repeat-By:
---------
L = [1,0,0,0; 2,1,0,0; 3,4,1,0; 5,6,7,1];
U = [1,2,3,4; 0,5,6,7; 0,0,8,9; 0,0,0,10];
A = L*U;
%A = [1,2,3,4; 2,9,12,15; 3,26,41,49; 5,40,107,135];
[L2,U2] = lu(A);
Fix:
---
* If possible, replace this item with a description of how to
fix the problem (if you don't have a fix for the problem, don't
include this section, but please do submit your report anyway).
Configuration (please do not edit this section):
-----------------------------------------------
uname output: Linux miro-notebook 2.6.22-14-generic #1 SMP Tue Dec 18 08:02:57 UTC 2007 i686 GNU/Linux
configure opts: '--prefix=/usr' '--datadir=/usr/share' '--libdir=/usr/lib' '--libexecdir=/usr/lib' '--infodir=/usr/share/info' '--mandir=/usr/share/man' '--with-blas=-lblas-3' '--with-lapack=-llapack-3' '--with-hdf5' '--with-fftw' '--with-f77=/usr/bin/gfortran' '--enable-shared' '--enable-rpath' '--disable-static' '--build' 'i486-linux-gnu' 'build_alias=i486-linux-gnu' 'CC=/usr/bin/gcc' 'CXX=/usr/bin/g++' 'F77=/usr/bin/gfortran'
Fortran compiler: /usr/bin/gfortran
FFLAGS: -O2
F2C:
F2CFLAGS:
FLIBS: -L/usr/lib/gcc/i486-linux-gnu/4.1.2 -L/usr/lib/gcc/i486-linux-gnu/4.1.2/../../../../lib -L/lib/../lib -L/usr/lib/../lib -lhdf5 -lz -lgfortranbegin -lgfortran -lm
CPPFLAGS:
INCFLAGS: -I. -I. -I./liboctave -I./src -I./libcruft/misc
C compiler: /usr/bin/gcc, version 4.1.2 20061103 (prerelease) (Ubuntu 4.1.1-18ubuntu2)
CFLAGS: -O2
CPICFLAG: -fPIC
C++ compiler: /usr/bin/g++, version 4.1.2
CXXFLAGS: -O2
CXXPICFLAG: -fPIC
LD_CXX: /usr/bin/g++
LDFLAGS: -s
LIBFLAGS: -L.
RLD_FLAG: -Wl,-rpath -Wl,/usr/lib/octave-2.1.73
BLAS_LIBS: -llapack-3 -lblas-3
FFTW_LIBS: -lfftw3
LIBS: -lreadline -lncurses -ldl -lhdf5 -lz -lm
LEXLIB:
LIBPLPLOT:
LIBDLFCN:
LIBGLOB: %OCTAVE_CONF_LIBGLOB%
SED: /bin/sed
DEFS:
-DPACKAGE_NAME="" -DPACKAGE_TARNAME="" -DPACKAGE_VERSION=""
-DPACKAGE_STRING="" -DPACKAGE_BUGREPORT="" -DOCTAVE_SOURCE=1
-D_GNU_SOURCE=1 -DSTDC_HEADERS=1 -DHAVE_SYS_TYPES_H=1
-DHAVE_SYS_STAT_H=1 -DHAVE_STDLIB_H=1 -DHAVE_STRING_H=1
-DHAVE_MEMORY_H=1 -DHAVE_STRINGS_H=1 -DHAVE_INTTYPES_H=1 -DHAVE_STDINT_H=1
-DHAVE_UNISTD_H=1 -DSEPCHAR=':' -DSEPCHAR_STR=":" -D__NO_MATH_INLINES=1
-DCXX_NEW_FRIEND_TEMPLATE_DECL=1 -DCXX_ISO_COMPLIANT_LIBRARY=1
-DCXX_ABI=gnu_v3 -DHAVE_LIBM=1 -DHAVE_HDF5_H=1 -DHAVE_HDF5=1
-DHAVE_H5GGET_NUM_OBJS=1 -DHAVE_FFTW3=1 -DHAVE_IEEE754_DATA_FORMAT=1
-DF77_FUNC(name,NAME)=name ## _ -DF77_FUNC_(name,NAME)=name ## _
-DHAVE_BLAS=1 -DHAVE_GETHOSTNAME=1 -DHAVE_GETPWNAM=1 -DHAVE_DEV_T=1
-DHAVE_INO_T=1 -DHAVE_NLINK_T=1 -DHAVE_NLINK_T=1 -DHAVE_LONG_LONG_INT=1
-DHAVE_UNSIGNED_LONG_LONG_INT=1 -DHAVE_SIGSET_T=1 -DHAVE_SIG_ATOMIC_T=1
-DSIZEOF_SHORT=2 -DSIZEOF_INT=4 -DSIZEOF_LONG=4 -DSIZEOF_LONG_LONG=8
-DHAVE_ALLOCA_H=1 -DHAVE_ALLOCA=1 -DNPOS=std::string::npos
-DHAVE_PLACEMENT_DELETE=1 -DHAVE_DYNAMIC_AUTO_ARRAYS=1 -DSTDC_HEADERS=1
-DHAVE_DIRENT_H=1 -DTIME_WITH_SYS_TIME=1 -DHAVE_SYS_WAIT_H=1
-DHAVE_ASSERT_H=1 -DHAVE_CURSES_H=1 -DHAVE_DLFCN_H=1 -DHAVE_FCNTL_H=1
-DHAVE_FLOAT_H=1 -DHAVE_GRP_H=1 -DHAVE_LIMITS_H=1 -DHAVE_MEMORY_H=1
-DHAVE_NCURSES_H=1 -DHAVE_POLL_H=1 -DHAVE_PWD_H=1 -DHAVE_STDLIB_H=1
-DHAVE_STRING_H=1 -DHAVE_SYS_IOCTL_H=1 -DHAVE_SYS_PARAM_H=1
-DHAVE_SYS_POLL_H=1 -DHAVE_SYS_RESOURCE_H=1 -DHAVE_SYS_SELECT_H=1
-DHAVE_SYS_STAT_H=1 -DHAVE_SYS_TIME_H=1 -DHAVE_SYS_TIMES_H=1
-DHAVE_SYS_TYPES_H=1 -DHAVE_SYS_UTSNAME_H=1 -DHAVE_TERMCAP_H=1
-DHAVE_UNISTD_H=1 -DHAVE_SSTREAM=1 -DHAVE_TERMIO_H=1
-DHAVE_SGTTY_H=1 -DHAVE_ATEXIT=1 -DHAVE_BASENAME=1 -DHAVE_BCOPY=1
-DHAVE_BZERO=1 -DHAVE_CANONICALIZE_FILE_NAME=1 -DHAVE_DUP2=1
-DHAVE_ENDGRENT=1 -DHAVE_ENDPWENT=1 -DHAVE_EXECVP=1 -DHAVE_FCNTL=1
-DHAVE_FORK=1 -DHAVE_GETCWD=1 -DHAVE_GETEGID=1 -DHAVE_GETEUID=1
-DHAVE_GETGID=1 -DHAVE_GETGRENT=1 -DHAVE_GETGRGID=1 -DHAVE_GETGRNAM=1
-DHAVE_GETPGRP=1 -DHAVE_GETPID=1 -DHAVE_GETPPID=1 -DHAVE_GETPWENT=1
-DHAVE_GETPWUID=1 -DHAVE_GETTIMEOFDAY=1 -DHAVE_GETUID=1 -DHAVE_GETWD=1
-DHAVE_KILL=1 -DHAVE_LINK=1 -DHAVE_LOCALTIME_R=1 -DHAVE_LSTAT=1
-DHAVE_MEMMOVE=1 -DHAVE_MKDIR=1 -DHAVE_MKFIFO=1 -DHAVE_MKSTEMP=1
-DHAVE_ON_EXIT=1 -DHAVE_PIPE=1 -DHAVE_POLL=1 -DHAVE_PUTENV=1
-DHAVE_RAISE=1 -DHAVE_READLINK=1 -DHAVE_RENAME=1 -DHAVE_RINDEX=1
-DHAVE_RMDIR=1 -DHAVE_ROUND=1 -DHAVE_SELECT=1 -DHAVE_SETGRENT=1
-DHAVE_SETPWENT=1 -DHAVE_SETVBUF=1 -DHAVE_SIGACTION=1 -DHAVE_SIGLONGJMP=1
-DHAVE_SIGPENDING=1 -DHAVE_SIGPROCMASK=1 -DHAVE_SIGSUSPEND=1 -DHAVE_STAT=1
-DHAVE_STRCASECMP=1 -DHAVE_STRDUP=1 -DHAVE_STRERROR=1 -DHAVE_STRFTIME=1
-DHAVE_STRNCASECMP=1 -DHAVE_STRPTIME=1 -DHAVE_SYMLINK=1 -DHAVE_TEMPNAM=1
-DHAVE_UMASK=1 -DHAVE_UNLINK=1 -DHAVE_USLEEP=1 -DHAVE_VFPRINTF=1
-DHAVE_VSPRINTF=1 -DHAVE_VSNPRINTF=1 -DHAVE_WAITPID=1 -DHAVE_LIBDL=1
-DHAVE_DLOPEN=1 -DHAVE_DLSYM=1 -DHAVE_DLERROR=1 -DHAVE_DLCLOSE=1
-DHAVE_DLOPEN_API=1 -DENABLE_DYNAMIC_LINKING=1 -DHAVE_TIMEVAL=1
-DHAVE_FINITE=1 -DHAVE_ISNAN=1 -DHAVE_ISINF=1 -DHAVE_COPYSIGN=1
-DHAVE_DECL_SIGNBIT=1 -DHAVE_ACOSH=1 -DHAVE_ASINH=1 -DHAVE_ATANH=1
-DHAVE_ERF=1 -DHAVE_ERFC=1 -DHAVE_STRUCT_STAT_ST_BLKSIZE=1
-DHAVE_STRUCT_STAT_ST_BLOCKS=1 -DHAVE_STRUCT_STAT_ST_RDEV=1
-DHAVE_STRUCT_TM_TM_ZONE=1 -DHAVE_TM_ZONE=1 -DUSE_READLINE=1
-DEXCEPTION_IN_MATH=1 -DRETSIGTYPE=void -DSYS_SIGLIST_DECLARED=1
-DHAVE_SYS_SIGLIST=1 -DHAVE_POSIX_SIGNALS=1 -DHAVE_GETRUSAGE=1
-DHAVE_TIMES=1 -DGNUPLOT_BINARY="gnuplot" -DGNUPLOT_HAS_FRAMES=
User-preferences (please do not edit this section):
--------------------------------------------------
DEFAULT_EXEC_PATH = "/usr/lib/octave/2.1.73/site/exec/i486-pc-linux-gnu:/usr/lib/octave/site/exec/i486-pc-linux-gnu:/usr/lib/octave/2.1.73/exec/i486-pc-linux-gnu:/usr/bin"
DEFAULT_LOADPATH = ".:/usr/lib/octave/2.1.73/site/oct/i486-pc-linux-gnu//:/usr/lib/octave/site/oct/api-v13/i486-pc-linux-gnu//:/usr/lib/octave/site/oct/i486-pc-linux-gnu//:/usr/share/octave/2.1.73/site/m//:/usr/share/octave/site/api-v13/m//:/usr/share/octave/site/m//:/usr/lib/octave/2.1.73/oct/i486-pc-linux-gnu//:/usr/share/octave/2.1.73/m//"
EDITOR = "emacs"
EXEC_PATH = ":/usr/local/java/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games"
IMAGEPATH = ".:/usr/share/octave/2.1.73/imagelib//"
INFO_FILE = "/usr/share/info/octave2.1.info"
INFO_PROGRAM = "info"
LOADPATH = ":/usr/local/share/octave/site-m//:"
PAGER = "pager"
PS1 = "\\s:\\#> "
PS2 = "> "
PS4 = "+ "
automatic_replot = 1
beep_on_error = 0
completion_append_char = " "
crash_dumps_octave_core = 1
default_save_format = "ascii"
echo_executing_commands = 0
fixed_point_format = 0
gnuplot_binary = "gnuplot"
gnuplot_command_end = "\n"
gnuplot_command_plot = "pl"
gnuplot_command_replot = "rep"
gnuplot_command_splot = "sp"
gnuplot_command_title = "t"
gnuplot_command_using = "u"
gnuplot_command_with = "w"
gnuplot_has_frames = 1
history_file = "/home/miro/.octave_hist"
history_size = 1024
ignore_function_time_stamp = "system"
max_recursion_depth = 256
output_max_field_width = 10
output_precision = 5
page_output_immediately = 0
page_screen_output = 1
print_answer_id_name = 1
print_empty_dimensions = 1
print_rhs_assign_val = 0
# return_last_computed_value =
save_precision = 15
saving_history = 1
sighup_dumps_octave_core = 1
sigterm_dumps_octave_core = 1
silent_functions = 0
split_long_rows = 1
string_fill_char = " "
struct_levels_to_print = 2
suppress_verbose_help_message = 0
warn_assign_as_truth_value = 1
warn_divide_by_zero = 1
warn_empty_list_elements = 0
warn_fortran_indexing = 0
warn_function_name_clash = 1
warn_future_time_stamp = 1
warn_imag_to_real = 0
warn_missing_semicolon = 0
warn_neg_dim_as_zero = 0
warn_num_to_str = 1
warn_resize_on_range_error = 0
warn_separator_insert = 0
warn_single_quote_string = 0
warn_str_to_num = 0
warn_undefined_return_values = 1
warn_variable_switch_label = 0
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