### E.4 Installation Problems

This section contains a list of problems (and some apparent problems that don’t really mean anything is wrong) that may show up during installation of Octave.

- On some SCO systems, `info` fails to compile if `HAVE_TERMIOS_H` is defined in `config.h`. Simply removing the definition from `info/config.h` should allow it to compile.
- If `configure` finds `dlopen`, `dlsym`, `dlclose`, and `dlerror`, but not the header file `dlfcn.h`, you need to find the source for the header file and install it in the directory `usr/include`. This is reportedly a problem with Slackware 3.1. For Linux/GNU systems, the source for `dlfcn.h` is in the `ldso` package.
- Building `.oct` files doesn’t work.

  You should probably have a shared version of `libstdc++`. A patch is needed to build shared versions of version 2.7.2 of `libstdc++` on the HP-PA architecture. You can find the patch at ftp://ftp.cygnus.com/pub/g++/libg++-2.7.2-hppa-gcc-fix.

- On some DEC alpha systems there may be a problem with the `libdxml` library, resulting in floating point errors and/or segmentation faults in the linear algebra routines called by Octave. If you encounter such problems, then you should modify the configure script so that `SPECIAL_MATH_LIB` is not set to `-ldxml`.
- On FreeBSD systems Octave may hang while initializing some internal constants. The fix appears to be to use

      options      GPL_MATH_EMULATE

  rather than

      options      MATH_EMULATE

  in the kernel configuration files (typically found in the directory `/sys/i386/conf`). After making this change, you’ll need to rebuild the kernel, install it, and reboot.

- If you encounter errors like

      passing `void (*)()' as argument 2 of
        `octave_set_signal_handler(int, void (*)(int))'

  or

      warning: ANSI C++ prohibits conversion from `(int)'
               to `(…)'

  while compiling `sighandlers.cc`, you may need to edit some files in the `gcc` include subdirectory to add proper prototypes for functions there. For example, Ultrix 4.2 needs proper declarations for the `signal` function and the `SIG_IGN` macro in the file `signal.h`.

  On some systems the `SIG_IGN` macro is defined to be something like this:

      #define  SIG_IGN  (void (*)())1

  when it should really be something like:

      #define  SIG_IGN  (void (*)(int))1

  to match the prototype declaration for the `signal` function. This change should also be made for the `SIG_DFL` and `SIG_ERR` symbols. It may be necessary to change the definitions in `sys/signal.h` as well.

  The `gcc` `fixincludes` and `fixproto` scripts should probably fix these problems when `gcc` installs its modified set of header files, but I don’t think that’s been done yet.

  You should not change the files in `/usr/include`. You can find the `gcc` include directory tree by running the command

      gcc -print-libgcc-file-name

  The directory of `gcc` include files normally begins in the same directory that contains the file `libgcc.a`.

- Some of the Fortran subroutines may fail to compile with older versions of the Sun Fortran compiler. If you get errors like

      zgemm.f:
              zgemm:
      warning: unexpected parent of complex expression subtree
      zgemm.f, line 245: warning: unexpected parent of complex
        expression subtree
      warning: unexpected parent of complex expression subtree
      zgemm.f, line 304: warning: unexpected parent of complex
        expression subtree
      warning: unexpected parent of complex expression subtree
      zgemm.f, line 327: warning: unexpected parent of complex
        expression subtree
      pcc_binval: missing IR_CONV in complex op
      make[2]: *** [zgemm.o] Error 1

  when compiling the Fortran subroutines in the `liboctave/external` subdirectory, you should either upgrade your compiler or try compiling with optimization turned off.

- On NeXT systems, if you get errors like this:

      /usr/tmp/cc007458.s:unknown:Undefined local
            symbol LBB7656
      /usr/tmp/cc007458.s:unknown:Undefined local
            symbol LBE7656

  when compiling `Array.cc` and `Matrix.cc`, try recompiling these files without `-g`.

- Some people have reported that calls to system() and the pager do not work on SunOS systems. This is apparently due to having `G_HAVE_SYS_WAIT` defined to be 0 instead of 1 when compiling `libg++`.
- On systems where the reference BLAS library is used the following matrix-by-vector multiplication incorrectly handles NaN values of the form `NaN * 0`.

      [NaN, 1; 0, 0] * [0; 1]
      ⇒
      [ 1
        0 ]

      correct result ⇒
      [ NaN
        0   ]

  Install a different BLAS library such as OpenBLAS or ATLAS to correct this issue.

- On NeXT systems, linking to `libsys_s.a` may fail to resolve the following functions

      _tcgetattr
      _tcsetattr
      _tcflow

  which are part of `libposix.a`. Unfortunately, linking Octave with `-posix` results in the following undefined symbols.

      .destructors_used
      .constructors_used
      _objc_msgSend
      _NXGetDefaultValue
      _NXRegisterDefaults
      .objc_class_name_NXStringTable
      .objc_class_name_NXBundle

  One kluge around this problem is to extract `termios.o` from `libposix.a`, put it in Octave’s `src` directory, and add it to the list of files to link together in the makefile. Suggestions for better ways to solve this problem are welcome!

- If Octave crashes immediately with a floating point exception, it is likely that it is failing to initialize the IEEE floating point values for infinity and NaN.

  If your system actually does support IEEE arithmetic, you should be able to fix this problem by modifying the function `octave_ieee_init` in the file `lo-ieee.cc` to correctly initialize Octave’s internal infinity and NaN variables.

  If your system does not support IEEE arithmetic but Octave’s configure script incorrectly determined that it does, you can work around the problem by editing the file `config.h` to not define `HAVE_ISINF`, `HAVE_FINITE`, and `HAVE_ISNAN`.

  In any case, please report this as a bug since it might be possible to modify Octave’s configuration script to automatically determine the proper thing to do.

- If Octave is unable to find a header file because it is installed in a location that is not normally searched by the compiler, you can add the directory to the include search path by specifying (for example) `CPPFLAGS=-I/some/nonstandard/directory` as an argument to `configure`. Other variables that can be specified this way are `CFLAGS`, `CXXFLAGS`, `FFLAGS`, and `LDFLAGS`. Passing them as options to the configure script also records them in the `config.status` file. By default, `CPPFLAGS` and `LDFLAGS` are empty, `CFLAGS` and `CXXFLAGS` are set to `"-g -O2"` and `FFLAGS` is set to `"-O"`.