/usr/share/doc/ruby-gsl/examples/vector/diff.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 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 | #!/usr/bin/env ruby
# Turn on warnings
$-w = true
require 'irb/xmp'
require 'gsl'
# Apparently, IRB::Frame has a bug that prevents the defaults from working, so
# an XMP instance must be created explicitly this way instead of using the
# otherwise convenient xmp method.
XMP.new(IRB::Frame.top(-1)).puts <<END
# Create Vector of x values
x = GSL::Vector.linspace(1, 5, 5)
# Create Vector y = x**5
y = GSL::pow_5(x)
# Compute succesive differences
y1 = y.diff
y2 = y1.diff
y3 = y2.diff
y4 = y3.diff
# Show that successive differences can be computed directly from y
y.diff(2) == y2
y.diff(3) == y3
y.diff(4) == y4
# Plot x and y Vectors
GSL::graph(x, y, y1, y2, y3, "-C -g 3 -l x -l y -x 1 5 1")
END
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