ruby-gsl Sample: cheb.rb

#!/usr/local/bin/ruby


require "GSL"
include GSL

# Test class Chebyshev
# visualize output with graph from plotuils:
# ruby cheb.rb > cheb.dat
# awk '{print $1,$2}' cheb.dat > 1.dat
# awk '{print $1,$3}' cheb.dat > 2.dat
# awk '{print $1,$4}' cheb.dat > 3.dat
# graph -Tps 1.dat -m 2 2.dat -m 3 3.dat > plot.ps

STDERR.puts "Running tests for Chebyshev Approximations..." 

f = Function::new { |x|
  if x < 0.5
	0.25
  else
	0.75
  end
}

i = 0
n = 10000

cs = Chebyshev::new(40, f, 0.0, 1.0)

while (i < n)
  i += 1
  x = i.to_f / n.to_f
  r10 = cs.eval_n(10, x)
  #res = cs.eval_n_err(10, x)
  r40 = cs.eval(x)
  #res = cs.eval_err(x)

  y = f[x]

  printf "%g %g %g %g\n", x, y, r10, r40
  #printf "%g (err = %g)\n", res.val, res.err
end

STDERR.puts "\ndone."