Why does D language do not support BigDecimal type?

Kagamin spam at here.lot
Tue Mar 12 09:12:13 UTC 2019


On Monday, 11 March 2019 at 15:23:34 UTC, BoQsc wrote:
> If it is unavoidable to use Floating point, how can I quickly 
> and simply understand the rules of using float to make the 
> least error, or should I just find a third party package for 
> that as well?

It's taught in a computational mathematics course. In short, you 
estimate how errors accumulate over operations in your algorithm, 
e.g. for a sum operation `x+y` of values with errors you have 
(x±dx)+(y±dy)±r, for which you calculate the range of values: 
minimum is x-dx+y-dy-r, maximum is x+dx+y+dy+r, so the error is 
dx+dy+r, where r is a rounding error, this error gets carried 
over to subsequent calculations. Similar for other operations. 
See for example 
https://en.wikipedia.org/wiki/Round-off_error#Accumulation_of_roundoff_error


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