/usr/share/doc/ruby-gsl/examples/pdf/poisson.rb is in ruby-gsl 2.1.0.3+dfsg1-1build1.
This file is owned by root:root, with mode 0o644.
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1 2 3 4 5 | #!/usr/bin/env ruby
require("gsl")
x = GSL::Vector[0..10]
y = GSL::Ran::poisson_pdf(x, 2.5)
y.graph_step(x, "-C -X x -Y 'p(x)' -L 'Poisson distribution, mu = 2.5' --toggle-rotate-y-label")
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