Installing Ruby's linalg in Ubuntu

Ruby has a project for download called linalg that exposes the LAPACK functions in Ruby. LAPACK is a set of routines written in Fortran to do Linear Algebra operations. Now, before you cry foul about Fortran, LAPACK is used in a lot of places, and it's pretty damn old and has held up over the years.

The linalg package just updated about two weeks ago, first since 2004, so it has some updates. Unfortunately, there's no easy gem to install. You'll have to download the tar, and then run

sudo ruby install.rb

Of course, you'll run into some problems, unless you have other packages installed:

sudo apt-get install lapack3 lapack3-dev libg2c0-dev 

Don't worry, if you don't like it, you can run uninstall. Read INSTALL file for more directions.
I use to wonder how people knew which packages to look for. Apparently, you look at the output and see what files the configure is crapping out on. Then use apt-file to search for which package the file is in. It's one of those basic things that seems not mentioning in hindsight. Like calling "source ~/.bashrc" after you've edited your bash files. No one ever mentions that.

sudo apt-get install apt-file
sudo apt-file update
apt-file list g2c.h

Knowing that, you'll know how to fish, and I'll not post how to install stuff in the future.

tip!

Capistrano and Mongrel are easy to use, but deployment is still hard

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"Installing" net/https library in Ruby

This isn't written anywhere that I've looked, so it's either obvious, or I just missed the boat. But basically, in order to use the "net/https" library, you don't need to download it. It's included in the build of Ruby 1.8.4+

However, what you do need to install is both openssl, and the ruby-openssl packages for it in ubuntu in order for it to be working. Tip!

How to install Ruby 1.8.5 from source on Ubuntu

Well, it ends up that installing Ruby 1.8.5 and the associated Gems is a pain on Ubuntu. I'm here to take away that pain, yo.

Installing Ruby 1.8.5 from source

First, get the source tarball of 1.8.5 from the ruby lang web page, and put it in /usr/local/src

sudo tar -xvzf ruby-1.8.5-p12
cd ruby-1.8.5-p12
sudo ./configure
sudo make
sudo make install

If all goes well, you're in business. But if it complains about "cannot open crt1.o"
(which is likely on Ubuntu), you'll divine on google that it needs a "glibc-devel-2.3.3-74.i386" package. But I've done the legwork already, and under ubuntu, it's actually called "libc6-dev"

sudo apt-get install libc6-dev

So try making Ruby again. It should be ok. If not, well, it's not documented here, since I didn't run into that problem.

What I did run into was more pain installing Gems.

Installing Ruby Gems from source

Again, go get the source tarball of ruby gems, and put it into /usr/local/src

sudo tar -xvzf rubygems-0.9.1
cd rubygems-0.9.1
sudo ruby setup.rb

Now, if all is well, you're golden. But since this is Ubuntu, it's likely that you're missing zlib. So, some people seemed to have been able to get it to work from using the "zlib-ruby" package. What I had to do was install zlib from source.

Installing Ruby Zlib from source

Get the Ruby Zlib source and again put it into /usr/local/src/

sudo tar -xvzf ruby-zlib-0.6.0
cd ruby-zlib-0.6.0
sudo ruby extconf.rb

If that didn't work, most likely, you got a bunch of stuff that said:

checking for deflateReset() in -lz... no
checking for deflateReset() in -llibz... no
checking for deflateReset() in -lzlib... no

That means that you need the headers for zlib. So install the package "zlib1g-dev"

sudo apt-get install zlib1g-dev

Then try it again. That should work, and once you get zlib installed, you can get gems up and running.