Bug #13754
Updated by lionel_perrin (Lionel PERRIN) over 7 years ago
Hello,
I'm not sure if I've misunderstood the bigdecimal class but in the following example, I only get 12 significant digits using bigdecimal while using Float, I get a correct value with 17 significant digits.
~~~ ruby
# using floats
101/0.9163472602589686 # 110.22022368622177 (OK: floating point computation)
# using bigdecimal
a = BigDecimal('101'); a.precs # [9, 18]
b = BigDecimal('0.9163472602589686'); b.precs # [18, 27]
c = a/b; c.precs # [18, 36] (OK: I understand that c is computed with 18 significant digits)
c.to_s # "0.110220223686e3" (Mmm: I see only 12 significant digits)
c - BigDecimal('0.110220223686e3') # 0.0 (Looks like c only stores 12 significant digits and not 18)
~~~
Using the Rational class, I've seen that the value I'm expecting is about:
~~~ ruby
BigDecimal.new(Rational(101/Rational('0.9163472602589686')), 25) 18) # 0.1102202236862217746799312e3 0.110220223686221775e3
~~~