I am way out of my element trying to build numpy on Windows, but we are having a replicable (though somewhat inconsistently on some machines) problem using fmin_cg on Windows that I am trying to debug. I'm on Windows 7 64-bit with Python 2.6.4 First, I try to build numpy. It complains about having no C:\windows\system32\python26.dll, but note C:\Users\skipper>dir %windir%\system32\python26.dll Volume in drive C has no label. Volume Serial Number is 182E-23CE Directory of C:\Windows\system32 10/26/2009 08:36 AM 2,764,288 python26.dll 1 File(s) 2,764,288 bytes 0 Dir(s) 72,496,721,920 bytes free C:\Users\skipper\source\numpy>python setup.py config --compiler=mingw32 build -- compiler=mingw32 bdist_wininst Running from numpy source directory.Forcing DISTUTILS_USE_SDK=1 F2PY Version 2_8480 blas_opt_info: blas_mkl_info: libraries mkl,vml,guide not found in C:\Users\skipper\source\atlaslib32 NOT AVAILABLE atlas_blas_threads_info: Setting PTATLAS=ATLAS libraries ptf77blas,ptcblas,atlas not found in C:\Users\skipper\source\atlasli b32 NOT AVAILABLE atlas_blas_info: FOUND: libraries = ['f77blas', 'cblas', 'atlas'] library_dirs = ['C:\\Users\\skipper\\source\\atlaslib32'] language = c C:\Users\skipper\source\numpy\numpy\distutils\command\config.py:397: Deprecation Warning: +++++++++++++++++++++++++++++++++++++++++++++++++ Usage of get_output is deprecated: please do not use it anymore, and avoid configuration checks involving running executable on the target machine. +++++++++++++++++++++++++++++++++++++++++++++++++ DeprecationWarning) No module named msvccompiler in numpy.distutils; trying from distutils FOUND: libraries = ['f77blas', 'cblas', 'atlas'] library_dirs = ['C:\\Users\\skipper\\source\\atlaslib32'] language = c define_macros = [('ATLAS_INFO', '"\\"?.?.?\\""')] lapack_opt_info: lapack_mkl_info: mkl_info: libraries mkl,vml,guide not found in C:\Users\skipper\source\atlaslib32 NOT AVAILABLE NOT AVAILABLE atlas_threads_info: Setting PTATLAS=ATLAS libraries ptf77blas,ptcblas,atlas not found in C:\Users\skipper\source\atlasli b32 libraries lapack_atlas not found in C:\Users\skipper\source\atlaslib32 numpy.distutils.system_info.atlas_threads_info NOT AVAILABLE atlas_info: libraries lapack_atlas not found in C:\Users\skipper\source\atlaslib32 numpy.distutils.system_info.atlas_info FOUND: libraries = ['lapack', 'f77blas', 'cblas', 'atlas'] library_dirs = ['C:\\Users\\skipper\\source\\atlaslib32'] language = f77 No module named msvccompiler in numpy.distutils; trying from distutils FOUND: libraries = ['lapack', 'f77blas', 'cblas', 'atlas'] library_dirs = ['C:\\Users\\skipper\\source\\atlaslib32'] language = f77 define_macros = [('ATLAS_INFO', '"\\"?.?.?\\""')] non-existing path in '': 'site.cfg.example' running config running build running config_cc unifing config_cc, config, build_clib, build_ext, build commands --compiler opti ons running config_fc unifing config_fc, config, build_clib, build_ext, build commands --fcompiler opt ions running build_src build_src building py_modules sources building library "npymath" sources Looking for python26.dll Building import library (arch=AMD64): "C:\Python26\libs\libpython26.a" (from C:\ Windows\system32\python26.dll) C:\Windows\system32\python26.dll C:\Python26\libs\python26.def objdump.exe: 'C:\Windows\system32\python26.dll': No such file Traceback (most recent call last): File "setup.py", line 210, in <module> setup_package() File "setup.py", line 203, in setup_package configuration=configuration ) File "C:\Users\skipper\source\numpy\numpy\distutils\core.py", line 186, in set up return old_setup(**new_attr) File "C:\Python26\lib\distutils\core.py", line 152, in setup dist.run_commands() File "C:\Python26\lib\distutils\dist.py", line 975, in run_commands self.run_command(cmd) File "C:\Python26\lib\distutils\dist.py", line 995, in run_command cmd_obj.run() File "C:\Users\skipper\source\numpy\numpy\distutils\command\build.py", line 37 , in run old_build.run(self) File "C:\Python26\lib\distutils\command\build.py", line 134, in run self.run_command(cmd_name) File "C:\Python26\lib\distutils\cmd.py", line 333, in run_command self.distribution.run_command(command) File "C:\Python26\lib\distutils\dist.py", line 995, in run_command cmd_obj.run() File "C:\Users\skipper\source\numpy\numpy\distutils\command\build_src.py", lin e 152, in run self.build_sources() File "C:\Users\skipper\source\numpy\numpy\distutils\command\build_src.py", lin e 163, in build_sources self.build_library_sources(*libname_info) File "C:\Users\skipper\source\numpy\numpy\distutils\command\build_src.py", lin e 298, in build_library_sources sources = self.generate_sources(sources, (lib_name, build_info)) File "C:\Users\skipper\source\numpy\numpy\distutils\command\build_src.py", lin e 385, in generate_sources source = func(extension, build_dir) File "numpy\core\setup.py", line 673, in get_mathlib_info st = config_cmd.try_link('int main(void) { return 0;}') File "C:\Python26\lib\distutils\command\config.py", line 257, in try_link self._check_compiler() File "C:\Users\skipper\source\numpy\numpy\distutils\command\config.py", line 4 5, in _check_compiler old_config._check_compiler(self) File "C:\Python26\lib\distutils\command\config.py", line 107, in _check_compil er dry_run=self.dry_run, force=1) File "C:\Users\skipper\source\numpy\numpy\distutils\ccompiler.py", line 561, i n new_compiler compiler = klass(None, dry_run, force) File "C:\Users\skipper\source\numpy\numpy\distutils\mingw32ccompiler.py", line 91, in __init__ build_import_library() File "C:\Users\skipper\source\numpy\numpy\distutils\mingw32ccompiler.py", line 282, in build_import_library return _build_import_library_amd64() File "C:\Users\skipper\source\numpy\numpy\distutils\mingw32ccompiler.py", line 305, in _build_import_library_amd64 generate_def(dll_file, def_file) File "C:\Users\skipper\source\numpy\numpy\distutils\mingw32ccompiler.py", line 252, in generate_def if i == len(dump): UnboundLocalError: local variable 'i' referenced before assignment