From: Jim Freeze <jim@...>
Date: 2002-08-06T01:53:09+09:00
Subject: Is there a bug in Matrix or Complex?

Hi:

I found what I would call strange behavior with Matrix and Complex.

-> cat c.rb
require 'matrix'
require 'complex'

c1 = Complex.new(1,2)
c2 = Complex.new(3,4)
c3 = Complex.new(4,2)

m = Matrix[[c1,c2],[c3,c2]]
puts "m", m
m = m.to_f
puts "m.to_f", m
puts "m.inv.inv", m.inv.inv
puts "m.inv.inv.to_f", m.inv.inv.to_f
puts (m == m.inv.inv.to_f)

-> ruby c.rb
m
Matrix[[1+2i, 3+4i], [4+2i, 3+4i]]
m.to_f
Matrix[[1.0+2.0i, 3.0+4.0i], [4.0+2.0i, 3.0+4.0i]]
m.inv.inv
Matrix[[1.0+2i, 3.0+4i], [4.0+2i, 3+4i]]
m.inv.inv.to_f
Matrix[[1.0+2i, 3.0+4i], [4.0+2i, 3+4i]]
false

Why does taking the double inverse let the elements
go back to integers? And, why does #to_f not convert
each element to a float after taking the inverse?

Thanks

-- 
Jim Freeze
If only I had something clever to say for my comment...
~