/usr/share/doc/ruby-gsl/examples/roots/demo.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 25 26 27 28 | #!/usr/bin/env ruby
require("gsl")
solver = GSL::Root::FSolver.alloc(GSL::Root::FSolver::BISECTION)
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
IO.popen("graph -T X -C -g 3 -X Iterations -Y 'Root'\
--toggle-rotate-y-label\
-L 'x^2 - 5 = 0, #{solver.name}' -I e -S 4", "w") do |io|
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)
io.printf("%d %e %e\n", iter, r, (xu-xl)/2)
end
end
|