lookup slower than sum

Jaroslav Hajek highegg at gmail.com
Thu Jan 8 12:06:51 CST 2009 

On Thu, Jan 8, 2009 at 5:06 PM, Łukasz Sowiński <lukasz.sowinski at post.pl> wrote:
> Bug report for Octave 3.0.3 configured for i686-pc-linux-gnu
>
> Description:
> -----------
>
>  * It is about 10 times faster to execute
>      sum(v < p)
>    than
>      lookup(v, p)
>    Actually, I thought lookup does some fast (O(log n) complexity) binnary search comparing to linear (O(n) complexity) sum.
>
>  * This is a very minor problem.
>    .

Lookup is much faster in development version. In general, benchmarking
the development version is usually more reasonable.



>
> Repeat-By:
> ---------
>
>  * Please execute the following code:
>
>       point = .5;
>       v = sort(rand(1, 10^7));
>       timer=-cputime; lookup(v, point); disp(["lookup: " num2str(timer+cputime) "s." ]);
>       timer=-cputime; sum(v < point);   disp(["sum:    " num2str(timer+cputime) "s." ]);
>       clear v;
>
>
>
> Configuration (please do not edit this section):
> -----------------------------------------------
>
> uname output:     Linux gentoo 2.6.27-gentoo-r5 #2 SMP PREEMPT Sat Dec
> 13 16:04:21 Local time zone must be set-- i686 Intel(R) Core(TM)2 CPU
> T5500 @ 1.66GHz GenuineIntel GNU/Linux
> configure opts:   '--prefix=/usr' '--host=i686-pc-linux-gnu'
> '--mandir=/usr/share/man' '--infodir=/usr/share/info'
> '--datadir=/usr/share' '--sysconfdir=/etc' '--localstatedir=/var/lib'
> '--localstatedir=/var/state/octave' '--enable-shared'
> '--with-blas=-lblas  ' '--with-lapack=-llapack -lblas  '
> '--without-hdf5' '--without-curl' '--with-zlib' '--without-fftw'
> '--without-umfpack' '--without-colamd' '--without-ccolamd'
> '--without-cholmod' '--without-cxsparse' '--enable-readline'
> '--build=i686-pc-linux-gnu' 'build_alias=i686-pc-linux-gnu'
> 'host_alias=i686-pc-linux-gnu' 'CFLAGS=-O2 -march=prescott -pipe
> -fomit-frame-pointer' 'LDFLAGS=' 'CXXFLAGS=-O2 -march=prescott -pipe
> -fomit-frame-pointer'
> Fortran compiler: i686-pc-linux-gnu-gfortran
> FFLAGS:           -O -mieee-fp
> F2C:              @F2C@
> F2CFLAGS:         @F2CFLAGS@
> FLIBS:            -L/usr/lib/gcc/i686-pc-linux-gnu/4.1.2
> -L/usr/lib/gcc/i686-pc-linux-gnu/4.1.2/../../../../i686-pc-linux-gnu/lib
> -L/usr/lib/gcc/i686-pc-linux-gnu/4.1.2/../../.. -lz -lgfortranbegin
> -lgfortran -lm
> CPPFLAGS:
> INCFLAGS:         -I. -I. -I./liboctave -I./src -I./libcruft/misc
> C compiler:       i686-pc-linux-gnu-gcc, version 4.1.2 (Gentoo 4.1.2 p1.0.2)
> CFLAGS:           -O2 -march=prescott -pipe -fomit-frame-pointer
> CPICFLAG:         -fPIC
> C++ compiler:     i686-pc-linux-gnu-g++, version 4.1.2
> CXXFLAGS:         -O2 -march=prescott -pipe -fomit-frame-pointer
> CXXPICFLAG:       -fPIC
> LD_CXX:           i686-pc-linux-gnu-g++
> LDFLAGS:
> LIBFLAGS:         -L.
> RLD_FLAG:         -Wl,-rpath -Wl,/usr/lib/octave-3.0.3
> BLAS_LIBS:        -llapack -lblas   -lblas
> FFTW_LIBS:
> LIBS:             -lreadline  -lncurses -ldl -lz -lm
> LEXLIB:
> 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_QHULL=1 -DHAVE_PCRE=1 -DHAVE_REGEXEC=1 -DHAVE_REGEX=1
>  -DHAVE_ZLIB_H=1 -DHAVE_ZLIB=1 -DHAVE_GLPK_H=1 -DHAVE_GLPK=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_INTTYPES_H=1 -DHAVE_LIMITS_H=1 -DHAVE_LOCALE_H=1
>  -DHAVE_MEMORY_H=1 -DHAVE_NCURSES_H=1 -DHAVE_POLL_H=1 -DHAVE_PWD_H=1
>  -DHAVE_STDINT_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_UTIME_H=1 -DHAVE_SSTREAM=1
>  -DHAVE_TERMIO_H=1 -DHAVE_SGTTY_H=1 -DHAVE_GLOB_H=1 -DHAVE_FNMATCH_H=1
>  -DHAVE_FNMATCH=1 -DHAVE_GLOB=1 -DHAVE_ATEXIT=1 -DHAVE_BASENAME=1
>  -DHAVE_BCOPY=1 -DHAVE_BZERO=1 -DHAVE_CANONICALIZE_FILE_NAME=1
>  -DHAVE_CHMOD=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_LGAMMA=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_REALPATH=1 -DHAVE_RENAME=1 -DHAVE_RINDEX=1
>  -DHAVE_RMDIR=1 -DHAVE_ROUND=1 -DHAVE_SELECT=1 -DHAVE_SETGRENT=1
>  -DHAVE_SETLOCALE=1 -DHAVE_SETPWENT=1 -DHAVE_SETVBUF=1 -DHAVE_SIGACTION=1
>  -DHAVE_SIGLONGJMP=1 -DHAVE_SIGPENDING=1 -DHAVE_SIGPROCMASK=1
>  -DHAVE_SIGSUSPEND=1 -DHAVE_SNPRINTF=1 -DHAVE_STAT=1 -DHAVE_STRCASECMP=1
>  -DHAVE_STRDUP=1 -DHAVE_STRERROR=1 -DHAVE_STRNCASECMP=1 -DHAVE_STRPTIME=1
>  -DHAVE_STRSIGNAL=1 -DHAVE_SYMLINK=1 -DHAVE_TEMPNAM=1 -DHAVE_TGAMMA=1
>  -DHAVE_UMASK=1 -DHAVE_UNAME=1 -DHAVE_UNLINK=1 -DHAVE_USLEEP=1
>  -DHAVE_UTIME=1 -DHAVE_VFPRINTF=1 -DHAVE_VSPRINTF=1 -DHAVE_VSNPRINTF=1
>  -DHAVE_WAITPID=1 -DHAVE_STRFTIME=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_EXP2=1 -DHAVE_LOG2=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 -DHAVE_DECL_SYS_SIGLIST=1
>  -DHAVE_POSIX_SIGNALS=1 -DRETSIGTYPE_IS_VOID=1 -DHAVE_GETRUSAGE=1
>  -DHAVE_TIMES=1 -DYYTEXT_POINTER=1 -DGNUPLOT_BINARY="gnuplot"
>
> User-preferences (please do not edit this section):
> --------------------------------------------------
>
>  EDITOR = /bin/nano
>  EXEC_PATH =
> /usr/libexec/octave/3.0.3/site/exec/i686-pc-linux-gnu:/usr/libexec/octave/api-v32/site/exec/i686-pc-linux-gnu:/usr/libexec/octave/site/exec/i686-pc-linux-gnu:/usr/libexec/octave/3.0.3/exec/i686-pc-linux-gnu:/usr/bin:/usr/bin:/usr/local/bin:/usr/bin:/bin:/opt/bin:/usr/i686-pc-linux-gnu/gcc-bin/4.1.2:/opt/blackdown-jdk-1.4.2.03/bin:/opt/blackdown-jdk-1.4.2.03/jre/bin:/usr/qt/3/bin:/usr/games/bin
>  IMAGE_PATH = .:/usr/share/octave/3.0.3/imagelib
>  PAGER = /usr/bin/less
>  PS1 = \s:\#>
>  PS2 = >
>  PS4 = +
>  beep_on_error = 0
>  completion_append_char =
>  crash_dumps_octave_core = 1
>  echo_executing_commands = 0
>  fixed_point_format = 0
>  gnuplot_binary = gnuplot
>  gnuplot_command_end =
>
>  gnuplot_command_plot = pl
>  gnuplot_command_replot = rep
>  gnuplot_command_splot = sp
>  gnuplot_command_title = t
>  gnuplot_command_using = u
>  gnuplot_command_with = w
>  history_file = /home/lukasz/.octave_hist
>  history_size = 1024
>  ignore_function_time_stamp = none
>  info_file = /usr/share/info/octave.info
>  info_program = info
>  makeinfo_program = makeinfo
>  max_recursion_depth = 256
>  output_max_field_width = 5
>  output_precision = 5
>  page_output_immediately = 0
>  page_screen_output = 0
>  print_answer_id_name = 1
>  print_empty_dimensions = 1
>  save_precision = 16
>  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
>
>
>
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-- 
RNDr. Jaroslav Hajek
computing expert
Aeronautical Research and Test Institute (VZLU)
Prague, Czech Republic
url: www.highegg.matfyz.cz

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