# Using the GSL library **URL:** \ **Category:** Ruby\ **Created:** [May 8, 2009, 5:59am UTC](https://www.ruby-forum.com/t/using-the-gsl-library/167474 "2009-05-08T05:59:09Z")\ **Posts on this page:** 5\ **Page:** 1
**Author:** ![leveille](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/l/a88e57/32.png) [@leveille](https://www.ruby-forum.com/u/leveille)\ **Post date:** [May 8, 2009, 5:59am UTC](https://www.ruby-forum.com/t/using-the-gsl-library/167474/1 "2009-05-08T05:59:09Z")
I’m trying to get started with the gsl-ruby library - thought I’d start with calculating mean of an array. I’m following the example on [http://rb-gsl.rubyforge.org/stats.html](http://rb-gsl.rubyforge.org/stats.html). But I run into this: require(“gsl”) =\> true irb(main):002:0\> v = Vector[1…7] NameError: uninitialized constant Vector from (irb):2 Isn’t Vector in the core?.. so I did this irb(main):003:0\> require ‘matrix’ =\> true irb(main):004:0\> v = Vector[1…7] =\> Vector[1…7] irb(main):005:0\> v.mean NoMethodError: undefined method `mean’ for Vector[1…7]:Vector from (irb):5 It appears my GSL is not installed or something…? I would really appreciate some guidance. Thank you. I have installed libgsl-ruby1.8, libgsl0ldbl, libgsl-ruby, and gsl-bin ---
**Author:** ![leveille](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/l/a88e57/32.png) [@leveille](https://www.ruby-forum.com/u/leveille)\ **Post date:** [May 8, 2009, 7:12am UTC](https://www.ruby-forum.com/t/using-the-gsl-library/167474/2 "2009-05-08T07:12:27Z")
On Thu, May 7, 2009 at 22:59, Jason L. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > I’m trying to get started with the gsl-ruby library - thought I’d start > with calculating mean of an array. I’m following the example on > [http://rb-gsl.rubyforge.org/stats.html](http://rb-gsl.rubyforge.org/stats.html). But I run into this: > > require(“gsl”) > =\> true > irb(main):002:0\> v = Vector[1…7] > NameError: uninitialized constant Vector from (irb):2 I forget exactly when it happened, but the GSL namespace isn’t loaded by default in the newer versions of the library. This is a good thing. Your example will work if you type: v = GSL::Vector[1…7] if you really want the short versions, just type include GSL > Isn’t Vector in the core?.. so I did this > > irb(main):003:0\> require ‘matrix’ > =\> true > irb(main):004:0\> v = Vector[1…7] > =\> Vector[1…7] be careful here. What you just did was load the std library ‘matrix’ library, which also defined a Vector constructor - but no method called ‘mean’ This is very different than GSL. Cameron ---
**Author:** ![leveille](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/l/a88e57/32.png) [@leveille](https://www.ruby-forum.com/u/leveille)\ **Post date:** [May 8, 2009, 4:39pm UTC](https://www.ruby-forum.com/t/using-the-gsl-library/167474/3 "2009-05-08T16:39:54Z")
] > be careful here. What you just did was load the std library ‘matrix’ > library, which also defined a Vector constructor - but no method > called ‘mean’ This is very different than GSL. Thank you. I see that GSL methods must take only GSL::Vectors as arguments rather than ‘matrix’ Vectors: irb(main):032:0\> a = [1,5,7,2] =\> [1, 5, 7, 2] irb(main):033:0\> v1 = GSL::Vector.alloc(a) =\> GSL::Vector [1.000e+00 5.000e+00 7.000e+00 2.000e+00] irb(main):034:0\> v2 = Vector.elements(a) =\> Vector[1, 5, 7, 2] irb(main):035:0\> GSL::Stats::mean(v1) =\> 3.75 irb(main):036:0\> GSL::Stats::mean(v2) TypeError: wrong argument type Vector from (irb):36:in `mean’ from (irb):36 It seems a little odd that we have two kinds of vectors but they are both a ‘vector’ ---
**Author:** ![leveille](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/l/a88e57/32.png) [@leveille](https://www.ruby-forum.com/u/leveille)\ **Post date:** [May 8, 2009, 10:46pm UTC](https://www.ruby-forum.com/t/using-the-gsl-library/167474/4 "2009-05-08T22:46:36Z")
OK. that makes sense. I will be aware of the multiple external library issue. Thanks! ---
**Author:** ![leveille](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/l/a88e57/32.png) [@leveille](https://www.ruby-forum.com/u/leveille)\ **Post date:** [May 8, 2009, 10:26pm UTC](https://www.ruby-forum.com/t/using-the-gsl-library/167474/5 "2009-05-08T22:26:07Z")
On Fri, May 8, 2009 at 09:39, Jason L. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > > be careful here. What you just did was load the std library ‘matrix’ > > library, which also defined a Vector constructor - but no method > > called ‘mean’ This is very different than GSL. > It seems a little odd that we have two kinds of vectors but they are > both a ‘vector’ not really. “vector” in this case is just a name corresponding to a variable (objects of a class in two independent and non-compatible libraries). Both libraries provide an object meant to represent a mathematical “vector”, so their names make sense in both cases. Both are “add ons” to the language itself, which is why I cautioned you on their use. Be careful when one loads external libraries, there is no guarantee that different libraries will co-exist peacefully. The latter point is why I mentioned GSL::Vector being “a good thing” than “include GSL; Vector”. GSL is now wrapped in a “namespace” (module in rubyspeak) so it doesn’t cause confusion with the default namespace. It’s a subtle point when getting started, but a critical piece to keep in mind. Cameron