NTL: Trouble-shooting guide

NTL should compile and run without problems on any platform. However, there are some known problems with some of the software that NTL relies on. This page documents the known problems, and suggests work-arounds.

• On older versions of Microsoft Visual C++, you may get error messages like "floor is not a member of std". If that happens, you have to turn off the NTL_STD_CXX flag by editing the file include/NTL/config.h.

• On some Unix platforms and with some versions of the gcc compiler, the compiler may crash with an internal error while compiling a few of NTL's files. Most notably, gcc 2.95.2 causes problems on some platforms, especially Alphas.

  One possible work-around is to add the flag -fno-exceptions to CFLAGS when compiling (edit the makefile to do this, or run the configure script with an appropriate argument).

  NTL does not use any exceptions, and so it should be OK to turn them off. It appears that some of the exception-handling code in the gcc compiler is buggy.

  If that does not work, another possible work-around is to compile the few NTL files that cause the problem without optimization, i.e., to remove the -O2 flag from CFLAGS. Of course, if you do this, you lose some performance.

• The extended Euclidean algorithm in GMP version 3.1.1 has a bug. When using NTL with GMP as the primary long integer package, this bug can (under very rare circumstances) cause NTL to crash, with an "internal error" message.

  Use a more recent version of GMP to avoid this problem.

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