From: bradjpeek <bradjpeek@...>
Date: 2006-11-13T10:55:09+09:00
Subject: Ruby floating point behavior typical of other langs??


The second edition of _The_Ruby_Way_ has an example similar to the
following:

irb(main):001:0> puts 'not equal' unless (3.2 - 2.0) == 1.2
not equal
=>nil

The point is to illustrate why you might want to use BigDecimal (i.e.
so 3.2 - 2.0 would in fact = 1.2).

require 'bigdecimal'
x = BigDecimal("3.2")
y = BigDecimal("2.0")
z = BigDecimal("1.2")
p x - y == z ?  "equal" : "not equal"    # prints "equal"

I'm fairly new to Ruby and don't do much programming, but when I saw
this example I was surprised that the default behavior is that 3.2 -
2.0 != 1.2

To me, this violates the "Principal of least surprise", but I guess it
isn't a big deal because I don't remember it being discussed in
Programming Ruby book (but it certainly may have been).

Do other languages work this way?