# Error installing gem

**URL:** <https://www.ruby-forum.com/t/error-installing-gem/107570>\
**Category:** Ruby\
**Created:** [June 23, 2007, 2:50pm UTC](https://www.ruby-forum.com/t/error-installing-gem/107570 "2007-06-23T14:50:56Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![unknown](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/u/4bbf92/32.png) [@unknown](https://www.ruby-forum.com/u/unknown)\
**Post date:** [June 23, 2007, 2:50pm UTC](https://www.ruby-forum.com/t/error-installing-gem/107570/1 "2007-06-23T14:50:56Z")

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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

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<div class="post-metadata">

**Author:** ![unknown](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/u/4bbf92/32.png) [@unknown](https://www.ruby-forum.com/u/unknown)\
**Post date:** [June 23, 2007, 4:17pm UTC](https://www.ruby-forum.com/t/error-installing-gem/107570/2 "2007-06-23T16:17:05Z")

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Hello Dominik,

the error you get is due to the fact that the  
gem you are trying to install is building the software  
from source code.  
This is usually done in three steps -

configure/make/make install …  
but the Windows version of nmake is not installed on your computer.  
You can install a compiler, such as MinGW :

[http://www.mingw.org/](http://www.mingw.org/)

on your system to do the compilation.

This can be useful in many cases anyway…  
I haven’t worked with specific backpropagation software, but  
if you want to use Ruby for scientific work, some general  
numerics software such as Ruby-GSL ([http://rb-gsl.rubyforge.org/](http://rb-gsl.rubyforge.org/))  
which is included in the one-click installer for Windows

[http://rubyforge.org/frs/?group\_id=167](http://rubyforge.org/frs/?group_id=167)

may be helpful.

Best regards,

Axel

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<div class="post-metadata">

**Author:** ![unknown](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/u/4bbf92/32.png) [@unknown](https://www.ruby-forum.com/u/unknown)\
**Post date:** [June 24, 2007, 8:05pm UTC](https://www.ruby-forum.com/t/error-installing-gem/107570/3 "2007-06-24T20:05:35Z")

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Thanks for the answer.  
I’ll have a look for it.

Dominik

2007/6/23, Axel E. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid):