Export RoundUp/RoundDown method

[lovung]

We only have Round method at

decimal/decimal.go

Lines 792 to 819 in 480f653

	// Round rounds the decimal to places decimal places.
	// If places < 0, it will round the integer part to the nearest 10^(-places).
	//
	// Example:
	//
	// NewFromFloat(5.45).Round(1).String() // output: "5.5"
	// NewFromFloat(545).Round(-1).String() // output: "550"
	//
	func (d Decimal) Round(places int32) Decimal {
	// truncate to places + 1
	ret := d.rescale(-places - 1)
	// add sign(d) * 0.5
	if ret.value.Sign() < 0 {
	ret.value.Sub(ret.value, fiveInt)
	} else {
	ret.value.Add(ret.value, fiveInt)
	}
	// floor for positive numbers, ceil for negative numbers
	_, m := ret.value.DivMod(ret.value, tenInt, new(big.Int))
	ret.exp++
	if ret.value.Sign() < 0 && m.Cmp(zeroInt) != 0 {
	ret.value.Add(ret.value, oneInt)
	}
	return ret
	}

How about exposing the RoundDown and RoundUp method?

[njason]

There are Floor and Ceil, but they only round to integer values. Since adding optional parameters to these functions is not an option, I think it would make sense to add the new proposed functions. Added to backlog.

[mwoss]

Closing, implemented in #196 and merged to master.