From bug-octave-request at bevo dot che dot wisc dot edu Sun Jul 29 09:26:24 2001 Subject: exp(large pure imaginary) returns absurdly large result From: "Joseph P. Skudlarek" To: bug-octave at bevo dot che dot wisc dot edu Date: Sun, 29 Jul 2001 09:24:46 -0500 Bug report for Octave 2.0.14 configured for i386-redhat-linux-gnu Description: - ----------- The result of exp on a very large imaginary number returns a value that is way too big. In particular, exp(0.0000e+00 + 9.2238e+18i) -> 9.2238e+18 + 9.2238e+18i Repeat-By: - --------- Run the following demo function; transcript included below. ## -*- Mode: octave; indent-tabs-mode: nil fill-column: 72 -*- ## ######################################################################## function demo_exp_1e18_bug ## demonstrate horrid problem with exp(large imaginary) carrier = 2e6 ; Ts = 1e-6 /37 ; zing = 19838 ; zone = zing-1 : zing+1 ; args = I*2*pi*carrier*(zone)/Ts ; args data = exp(args) if (any(abs(data) > 1)) ## Zing! That's the bug -- the result of exp on a very large ## imaginary number returns a value that is way too big. error("|exp(large pure imaginary)| > 1") ; endif endfunction ##[] -| octave> demo_exp_1e18_bug -| args = -| -| Columns 1 and 2: -| -| 0.0000e+00 + 9.2233e+18i 0.0000e+00 + 9.2238e+18i -| -| Column 3: -| -| 0.0000e+00 + 9.2243e+18i -| -| data = -| -| Columns 1 and 2: -| -| 7.8262e-01 + 6.2250e-01i 9.2238e+18 + 9.2238e+18i -| -| Column 3: -| -| 9.2243e+18 + 9.2243e+18i -| -| error: |exp(large pure imaginary)| > 1 -| error: evaluating index expression near line 21, column 5 -| error: evaluating if command near line 18, column 3 -| error: called from `demo_exp_1e18_bug' in file `/mnt/win98/local/cypress/snap/dsp/demo_exp_1e18_bug.m' -| octave> 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 gyges 2.2.5-15 #1 Mon Apr 19 23:00:46 EDT 1999 i686 unknown configure opts: --prefix=/usr --with-g77 --enable-dl --enable-shared --enable-rpath --enable-lite-kernel --enable-picky-flags i386-redhat-linux Fortran compiler: g77 FFLAGS: -O F2C: F2CFLAGS: FLIBS: -lg2c -lm -L/usr/lib/gcc-lib/i386-redhat-linux/egcs-2.91.66 -L/usr/i386-redhat-linux/lib -lm CPPFLAGS: INCFLAGS: -I/usr/include -I/usr/include/octave-2.0.14 C compiler: gcc, version 2.91.66 19990314/Linux (egcs-1.1.2 release) CFLAGS: -DHAVE_CONFIG_H -mieee-fp -O2 CPICFLAG: -fPIC C++ compiler: c++, version 2.91.66 19990314/Linux (egcs-1.1.2 release) CXXFLAGS: -DHAVE_CONFIG_H -mieee-fp -fno-rtti -fno-exceptions -fno-implicit-templates -O2 CXXPICFLAG: -fPIC LDFLAGS: -g LIBFLAGS: -L/usr/lib/octave-2.0.14 RLD_FLAG: -Xlinker -rpath -Xlinker /usr/lib/octave-2.0.14 TERMLIBS: -lncurses LIBS: LEXLIB: LIBPLPLOT: LIBDLFCN: DEFS: -DOCTAVE_SOURCE=1 -DSEPCHAR=':' -DSEPCHAR_STR=":" -DUSE_READLINE=1 -D__NO_MATH_INLINES=1 -DCXX_NEW_FRIEND_TEMPLATE_DECL=1 -DHAVE_LIBM=1 -DF77_APPEND_UNDERSCORE=1 -DOCTAVE_LITE=1 -DSIZEOF_SHORT=2 -DSIZEOF_INT=4 -DSIZEOF_LONG=4 -DHAVE_ALLOCA_H=1 -DHAVE_ALLOCA=1 -DNPOS=string::npos -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_FNMATCH_H=1 -DHAVE_GLOB_H=1 -DHAVE_GRP_H=1 -DHAVE_LIMITS_H=1 -DHAVE_MEMORY_H=1 -DHAVE_NCURSES_H=1 -DHAVE_PWD_H=1 -DHAVE_SGTTY_H=1 -DHAVE_STDLIB_H=1 -DHAVE_STRING_H=1 -DHAVE_SYS_PARAM_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_TERMIO_H=1 -DHAVE_TERMIOS_H=1 -DHAVE_UNISTD_H=1 -DHAVE_VARARGS_H=1 -DHAVE_ATEXIT=1 -DHAVE_BCOPY=1 -DHAVE_BZERO=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_GETHOSTNAME=1 -DHAVE_GETPGRP=1 -DHAVE_GETPID=1 -DHAVE_GETPPID=1 -DHAVE_GETPWENT=1 -DHAVE_GETPWNAM=1 -DHAVE_GETPWUID=1 -DHAVE_GETTIMEOFDAY=1 -DHAVE_GETUID=1 -DHAVE_GETWD=1 -DHAVE_LSTAT=1 -DHAVE_MEMMOVE=1 -DHAVE_MKDIR=1 -DHAVE_MKFIFO=1 -DHAVE_ON_EXIT=1 -DHAVE_PIPE=1 -DHAVE_PUTENV=1 -DHAVE_RENAME=1 -DHAVE_RINDEX=1 -DHAVE_RMDIR=1 -DHAVE_SETGRENT=1 -DHAVE_SETPWENT=1 -DHAVE_SETVBUF=1 -DHAVE_SIGACTION=1 -DHAVE_SIGPENDING=1 -DHAVE_SIGPROCMASK=1 -DHAVE_SIGSUSPEND=1 -DHAVE_STAT=1 -DHAVE_STRCASECMP=1 -DHAVE_STRDUP=1 -DHAVE_STRERROR=1 -DHAVE_STRNCASECMP=1 -DHAVE_TEMPNAM=1 -DHAVE_UMASK=1 -DHAVE_UNLINK=1 -DHAVE_USLEEP=1 -DHAVE_VFPRINTF=1 -DHAVE_VSPRINTF=1 -DHAVE_WAITPID=1 -DHAVE_PROGRAM_INVOCATION_NAME=1 -DHAVE_LIBDL=1 -DHAVE_DLOPEN=1 -DHAVE_DLSYM=1 -DHAVE_DLERROR=1 -DHAVE_DLCLOSE=1 -DWITH_DL=1 -DWITH_DYNAMIC_LINKING=1 -DHAVE_FINITE=1 -DHAVE_ISNAN=1 -DHAVE_ISINF=1 -DHAVE_ACOSH=1 -DHAVE_ASINH=1 -DHAVE_ATANH=1 -DHAVE_ERF=1 -DHAVE_ERFC=1 -DHAVE_ST_BLKSIZE=1 -DHAVE_ST_BLOCKS=1 -DHAVE_ST_RDEV=1 -DHAVE_TM_ZONE=1 -DHAVE_GR_PASSWD=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_HAS_MULTIPLOT=1 -DGNUPLOT_HAS_FRAMES=1 User-preferences (please do not edit this section): - -------------------------------------------------- EDITOR = "emacs" EXEC_PATH = <> IMAGEPATH = ".:/usr/share/octave/2.0.14/imagelib//" INFO_FILE = "/usr/info/octave.info" INFO_PROGRAM = "info" LOADPATH = ":" PAGER = "less -e -P'-- less ?pB(%pB\\%):--. (f)orward, (b)ack, (q)uit$'" PS1 = "\\s> " PS2 = "> " PS4 = "+ " auto_unload_dot_oct_files = 0 automatic_replot = 0 beep_on_error = 0 completion_append_char = " " default_eval_print_flag = 1 # default_global_variable_value = default_return_value = [] default_save_format = "ascii" define_all_return_values = 0 do_fortran_indexing = 0 echo_executing_commands = 0 empty_list_elements_ok = "warn" fixed_point_format = 0 gnuplot_binary = "gnuplot" gnuplot_has_frames = 1 gnuplot_has_multiplot = 1 history_file = "/home/jskud/.octave_hist" history_size = 1024 ignore_function_time_stamp = "system" implicit_num_to_str_ok = 0 implicit_str_to_num_ok = 0 initialize_global_variables = 0 max_recursion_depth = 256 ok_to_lose_imaginary_part = "warn" output_max_field_width = 10 output_precision = 5 page_output_immediately = 0 page_screen_output = 0 prefer_column_vectors = 1 prefer_zero_one_indexing = 0 print_answer_id_name = 1 print_empty_dimensions = 1 propagate_empty_matrices = 1 resize_on_range_error = 1 return_last_computed_value = 0 save_precision = 15 saving_history = 1 silent_functions = 0 split_long_rows = 1 string_fill_char = " " struct_levels_to_print = 2 suppress_verbose_help_message = 0 treat_neg_dim_as_zero = 0 warn_assign_as_truth_value = 1 warn_comma_in_global_decl = 1 warn_divide_by_zero = 1 warn_function_name_clash = 1 warn_missing_semicolon = 0 warn_reload_forces_clear = 1 warn_variable_switch_label = 0 whitespace_in_literal_matrix = [] ------------------------------------------------------------- Octave is freely available under the terms of the GNU GPL. 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