Using Float For Currency

Using Float For Currency - Ruby Forum:

> What cracks can I lose money through? Floating point numbers represent an extremely wide range of values - much wider than their integer counterparts. This is handled through an exponent and mantissa. For this ability, they trade off precision. Think about the case of adding a large floating point number to a small floating point number: irb(main):001:0> a = 1.0e30 => 1.0e+030 irb(main):002:0> b = 1.0e-30 => 1.0e-030 irb(main):003:0> a + b => 1.0e+030 While this is an extreme example, it does demonstrate the loss of precision. Essentially, in floating point arithmetic we're trying to squeeze much more out of, say 32 or 48 or 64 bits. Integer arithmetic, on the other hand, is exact. And therefore so is fixed point arithmetic; however, fixed point doesn't enjoy the wide representation range as floats. The bottom line is you should never use floating point when it comes to ...

Full article: http://www.ruby-forum.com/topic/48754