/usr/share/doc/ruby-gsl/examples/gallery/lemniscate.rb is in ruby-gsl 2.1.0.3+dfsg1-1build1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 | #!/usr/bin/env ruby
require("gsl")
a = 1
t = GSL::Vector.linspace(0, 2*Math::PI, 100)
cost = GSL::Sf::cos(t)
sint = GSL::Sf::sin(t)
x = a*cost
y = a*sint*cost/(1 + sint*sint)
GSL::graph(x, y, "-T X -C")
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