/usr/share/doc/ruby-gsl/examples/roots/bisection.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 12 13 14 15 16 17 18 19 20 21 22 23 24 | #!/usr/bin/env ruby
require("gsl")
solver = GSL::Root::FSolver.alloc(GSL::Root::FSolver::BISECTION)
puts "Using #{solver.name} method"
f = GSL::Function.alloc { |x, params|
a = params[0]; b = params[1]; c = params[2]
(a*x + b)*x + c
}
f.set_params(1, 0, -5)
expected = Math::sqrt(5.0)
printf("%5s [%9s, %9s] %9s %10s %9s\n",
"iter", "lower", "upper", "root", "err", "err(est)")
solver.set(f, 0.0, 5.0)
iter = 0
status = nil
while status != GSL::SUCCESS
iter += 1
status = solver.iterate
r = solver.root; xl = solver.x_lower; xu = solver.x_upper
status = solver.test_interval(0, 0.001)
if status == GSL::SUCCESS; printf("Converged:\n"); end
printf("%5d [%.7f, %.7f] %.7f %+.7f %.7f\n",
iter, xl, xu, r, r - expected, xu - xl)
end
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