Hello everybody !

I just tried to install the "neuro"-gem. But the install process fails
with an exception:

C:\Windows\system32>gem install neuro -y
Building native extensions.  This could take a while...
ERROR:  While executing gem ... (Gem::Installer::ExtensionBuildError)
   ERROR: Failed to build gem native extension.

ruby extconf.rb install neuro -y
creating Makefile
E:/Ruby/lib/ruby/1.8/mkmf.rb:1102: warning: global variable `$preload'
not initialized

nmake
The command "nmake" couldn't be found.

Gem files will remain installed in
E:/Ruby/lib/ruby/gems/1.8/gems/neuro-0.4.0 for inspection.
Results logged to E:/Ruby/lib/ruby/gems/1.8/gems/neuro-0.4.0/ext/gem_make.out


Has anybody why this error occurs and how to solve it ???
Or are there other neuro-network / backpropagation extensions ?

Dominik