# Numerical Ruby - Segmentation faults, GSL trouble **URL:** \ **Category:** Ruby\ **Created:** [May 6, 2006, 10:59pm UTC](https://www.ruby-forum.com/t/numerical-ruby-segmentation-faults-gsl-trouble/94557 "2006-05-06T22:59:26Z")\ **Posts on this page:** 2\ **Page:** 1
**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:** [May 6, 2006, 10:59pm UTC](https://www.ruby-forum.com/t/numerical-ruby-segmentation-faults-gsl-trouble/94557/1 "2006-05-06T22:59:26Z")
Dear all, I have to determine the minima of a multiparameter mathematical function numerically. I try to use the simplex method, as implemented in Ruby-Gsl, to do this. Below is some code from an example as given in the documentation of Ruby/Gsl. However, when I run this on Cygwin (Windows XP), I get a segmentation fault from the line where the parameters are set, whereas in Fedora, I am not allowed to allocate even the function to minimize. Has anybody had this problem before ? Has anybody some self-written code for multidimensional minimization (preferably simplex method)? Thank you very much in advance, Best regards Axel * * * * * * #!/usr/bin/env ruby require(“gsl”) include GSL::MultiMin np = 2 my\_f = Proc.new { |v, params| x = v[0]; y = v[1] p0 = params[0]; p1 = params[1] 10.0\*(x - p0)_(x - p0) + 20.0_(y - p1)\*(y - p1) + 30.0 } my\_func = Function.alloc(my\_f, np) # ERROR in Fedora: undefined method `alloc’ for GSL::MultiMin::FMinimizer:Class (NoMethodError) my\_func.set\_params([1.0, 2.0]) # parameters: SEGMENTATION fault in Fedora. x = Vector.alloc([5, 7]) ss = Vector.alloc(np) ss.set\_all(1.0) minimizer = FMinimizer.alloc(“nmsimplex”, np) minimizer.set(my\_func, x, ss) iter = 0 begin iter += 1 status = minimizer.iterate() status = minimizer.test\_size(1e-2) if status == GSL::SUCCESS ``` puts("converged to minimum at") ``` end x = minimizer.x printf("%5d ", iter); for i in 0…np do ``` printf("%10.3e ", x[i]) ``` end printf(“f() = %7.3f size = %.3f\n”, minimizer.fval, minimizer.size); end while status == GSL::CONTINUE and iter \< 100 ---
**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:** [May 7, 2006, 1:13am UTC](https://www.ruby-forum.com/t/numerical-ruby-segmentation-faults-gsl-trouble/94557/2 "2006-05-07T01:13:05Z")
On Sun, 7 May 2006 removed\_email\_address@domain.invalid wrote: > to allocate even the function to minimize. > > Has anybody had this problem before ? Has anybody some self-written code > for multidimensional minimization (preferably simplex method)? > > Thank you very much in advance, > > Best regards > > Axel as to your first question, here are the results of running your code on my machine: jib:~ \> ruby a.rb 1 6.500e+00 5.000e+00 f() = 512.500 size = 1.082 2 5.250e+00 4.000e+00 f() = 290.625 size = 1.372 3 5.250e+00 4.000e+00 f() = 290.625 size = 1.372 4 5.500e+00 1.000e+00 f() = 252.500 size = 1.372 5 2.625e+00 3.500e+00 f() = 101.406 size = 1.823 6 2.625e+00 3.500e+00 f() = 101.406 size = 1.823 7 0.000e+00 3.000e+00 f() = 60.000 size = 1.823 8 2.094e+00 1.875e+00 f() = 42.275 size = 1.303 9 2.094e+00 1.875e+00 f() = 42.275 size = 1.303 10 2.578e-01 1.906e+00 f() = 35.684 size = 1.026 11 5.879e-01 2.445e+00 f() = 35.664 size = 0.804 12 1.258e+00 2.025e+00 f() = 30.680 size = 0.467 13 1.258e+00 2.025e+00 f() = 30.680 size = 0.356 14 1.093e+00 1.849e+00 f() = 30.539 size = 0.285 15 8.830e-01 2.004e+00 f() = 30.137 size = 0.168 16 8.830e-01 2.004e+00 f() = 30.137 size = 0.123 17 9.582e-01 2.060e+00 f() = 30.090 size = 0.100 18 1.022e+00 2.004e+00 f() = 30.005 size = 0.061 19 1.022e+00 2.004e+00 f() = 30.005 size = 0.042 20 1.022e+00 2.004e+00 f() = 30.005 size = 0.042 21 1.022e+00 2.004e+00 f() = 30.005 size = 0.027 22 1.022e+00 2.004e+00 f() = 30.005 size = 0.021 23 9.920e-01 1.997e+00 f() = 30.001 size = 0.015 24 9.920e-01 1.997e+00 f() = 30.001 size = 0.013 converged to minimum at 25 9.920e-01 1.997e+00 f() = 30.001 size = 0.008 your code was 100% un-modified. so i think your install isn’t good. i just installed the latest gsl, plotutils, and rb-gsl using export prefix=/dmsp/reference/ export LD\_RUN\_PATH=$prefix/lib export LD\_LIBRARY\_PATH=$prefix/lib for gsl : ./configure --prefix=$prefix && make && make install for plotutils : ./configure --prefix=$prefix && make && make install for rb-gsl : for w in config setup install;do ruby setup.rb $w;done eg. nothing special at all. so, sorry to say, it looks like you install is fubar. btw. my platform is jib:~ \> uname -srm && cat /etc/redhat-release && ruby -v Linux 2.4.21-40.ELsmp i686 Red Hat Enterprise Linux WS release 3 (Taroon Update 7) ruby 1.8.1 (2003-12-25) [i686-linux] so, while it’s not fedora, i’d be very suprised if it didn’t work there too. regards. -a