From: nobu@... Date: 2020-10-05T05:08:14+00:00 Subject: [ruby-core:100298] [Ruby master Bug#17214] BigDecimal exponentiation gives incorrect results Issue #17214 has been updated by nobu (Nobuyoshi Nakada). Status changed from Open to Rejected `BigDecimal` instances hold the precision, and it is not enough in that case. You need to override the default precision in some operations. ```ruby BigDecimal(2222).power(3.5, Float::DIG).to_i #=> 517135308457 ``` ---------------------------------------- Bug #17214: BigDecimal exponentiation gives incorrect results https://bugs.ruby-lang.org/issues/17214#change-87883 * Author: karatedog (F�ldes L�szl�) * Status: Rejected * Priority: Normal * ruby -v: ruby 2.7.1p83 (2020-03-31 revision a0c7c23c9c) [x86_64-linux] * Backport: 2.5: UNKNOWN, 2.6: UNKNOWN, 2.7: UNKNOWN ---------------------------------------- This is an incorrect value: ```ruby (BigDecimal("2222") ** BigDecimal("3.5")).to_i # => 517135311000 ``` This is the correct value (within Float precision): ```ruby 2222 ** 3.5 # => 517135308457.25256 ``` As the Base gets larger, the problem is more visible. Wrong value, number of trailing zeroes increase: ```ruby (BigDecimal("22222") ** BigDecimal("3.5")).to_i # => 1635840670000000 ``` Nearing maximum Float precision: ```ruby 22222 ** 3.5 # => 1635840670214066.5 ``` -- https://bugs.ruby-lang.org/ Unsubscribe: