/usr/share/doc/ruby-gsl/examples/histogram/ is in ruby-gsl 2.1.0.3+dfsg1-1build1.
This file is owned by root:root, with mode 0o755.
..
/usr/share/doc/ruby-gsl/examples/histogram/cauchy.rb
/usr/share/doc/ruby-gsl/examples/histogram/cauchy.sh
/usr/share/doc/ruby-gsl/examples/histogram/exponential.rb
/usr/share/doc/ruby-gsl/examples/histogram/gauss.rb
/usr/share/doc/ruby-gsl/examples/histogram/gsl-histogram.rb
/usr/share/doc/ruby-gsl/examples/histogram/histo2d.rb
/usr/share/doc/ruby-gsl/examples/histogram/histo3d.rb
/usr/share/doc/ruby-gsl/examples/histogram/histogram-pdf.rb
/usr/share/doc/ruby-gsl/examples/histogram/histogram.rb
/usr/share/doc/ruby-gsl/examples/histogram/integral.rb
/usr/share/doc/ruby-gsl/examples/histogram/poisson.rb
/usr/share/doc/ruby-gsl/examples/histogram/power.rb
/usr/share/doc/ruby-gsl/examples/histogram/rebin.rb
/usr/share/doc/ruby-gsl/examples/histogram/smp.dat
/usr/share/doc/ruby-gsl/examples/histogram/xexp.rb