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base repository: jruby/jruby
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  • 2 commits
  • 2 files changed
  • 2 contributors

Commits on Jan 29, 2015

  1. fix GH-2524 on master: improved algorithm to set the precision

    @k77ch7
    k77ch7 committed Jan 29, 2015
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    8fec7f4 View commit details

Commits on Jan 30, 2015

  1. Merge pull request #2537 from k77ch7/fix_GH-2524_on_master 

    Fix for issue 2524 on master: [BigDecimal] Loss of precision with different execution order
    @enebo
    enebo committed Jan 30, 2015
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    166445d View commit details
17 changes: 11 additions & 6 deletions core/src/main/java/org/jruby/ext/bigdecimal/RubyBigDecimal.java
View file
Original file line number Diff line number Diff line change
@@ -869,10 +869,16 @@ public IRubyObject op_quo20(ThreadContext context, IRubyObject other) {
}

private IRubyObject op_quo19_20(ThreadContext context, IRubyObject other) {
RubyObject preciseOther = getVpValue19(context, other, true);
RubyBigDecimal preciseOther = getVpValue19(context, other, true);
// regular division with some default precision
// TODO: proper algorithm to set the precision
return op_div(context, preciseOther, getRuntime().newFixnum(200));
// proper algorithm to set the precision
// the precision is multiple of 4
// and the precision is larger than len * 2
int len = value.precision() + preciseOther.value.precision();
int pow = len / 4;
int precision = (pow + 1) * 4 * 2;

return op_div(context, preciseOther, getRuntime().newFixnum(precision));
}

public IRubyObject op_div(ThreadContext context, IRubyObject other) {
@@ -923,10 +929,9 @@ public IRubyObject op_div(ThreadContext context, IRubyObject other, IRubyObject
// MRI behavior: "If digits is 0, the result is the same as the / operator."
if (scale == 0) return op_quo(context, other);

// TODO: better algorithm to set precision needed
int prec = Math.max(200, scale);
MathContext mathContext = new MathContext(scale, getRoundingMode(context.runtime));
return new RubyBigDecimal(context.runtime,
value.divide(val.value, new MathContext(prec, RoundingMode.HALF_UP))).setResult(scale);
value.divide(val.value, mathContext)).setResult(scale);
}

@JRubyMethod(name = "div")
12 changes: 12 additions & 0 deletions spec/regression/GH-2524_bigdecimal_loss_of_precision_with_different_excution_order_spec.rb
View file
Original file line number Diff line number Diff line change
@@ -0,0 +1,12 @@
require 'bigdecimal'

# https://github.com/jruby/jruby/issues/2524
describe 'BigDecimal precision test with different execution order' do
it 'returns same precision ' do
fraction = BigDecimal.new("0.0095") / 365 * BigDecimal.new(50_000)
r1 = fraction * BigDecimal.new(50_000) / BigDecimal.new(100_000)
r2 = fraction * (BigDecimal.new(50_000) / BigDecimal.new(100_000))
expect(r1).to eq(r2)
end
end