quickfix-developers

[Quickfix-developers] [qfj] double and not BigDecimal?

[Graham M. <gra...@gm...>]

Why was the decision made to use doubles instead of BigDecimals when
representing decimal data like prices?  (I guess maybe this was something
inherited from the old Java wrapper, but then the same can be asked about
the Javfa wrapper). It seems like the BigDecimal exact representations woul=
d
suit the application better, as dealing with rounding problems associated
with doubles can be a pain.  Of course arithmetic expressions are more
straightforward using doubles in Java, but you can always get around that b=
y
converting to doubles before doing any calculations.  Sitting here next to =
a
stock ticker, I just saw that Ford is down .07000000000001 cents today.
That's what I'm talking about.  Thoughts?

graham

Re: [Quickfix-developers] [qfj] double and not BigDecimal?

[Oren M. <or...@qu...>]

Did QuickFIX actually return this value to you or did you do some 
calculations on it before seeing this price?

--oren

Graham Miller wrote:

> Why was the decision made to use doubles instead of BigDecimals when 
> representing decimal data like prices?  (I guess maybe this was 
> something inherited from the old Java wrapper, but then the same can 
> be asked about the Javfa wrapper). It seems like the BigDecimal exact 
> representations would suit the application better, as dealing with 
> rounding problems associated with doubles can be a pain.  Of course 
> arithmetic expressions are more straightforward using doubles in Java, 
> but you can always get around that by converting to doubles before 
> doing any calculations.  Sitting here next to a stock ticker, I just 
> saw that Ford is down .07000000000001 cents today.  That's what I'm 
> talking about.  Thoughts?
>
> graham
>

Re: [Quickfix-developers] [qfj] double and not BigDecimal?

[Joerg T. <Joe...@ma...>]

Oren Miller wrote:
> QuickFIX Documentation:=20
> http://www.quickfixengine.org/quickfix/doc/html/index.html
> QuickFIX Support: http://www.quickfixengine.org/services.html
>=20
> Did QuickFIX actually return this value to you or did you do some=20
> calculations on it before seeing this price?

As a side note:

This issue has already been discussed a while ago; see the message thread=
s:

* QF java interface: conversion from double fields to BigDecimal give imp=
recise results
* price as double

For Java, a good default would be to use BigDecimal, but for C++ you woul=
d need a BCD lib.
So using the underlying string directly is the safest way at the moment.

Cheers, J=F6rg

--=20
Joerg Thoennes
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Tel.: +49 (0)241 44597-24      Macdonald Associates GmbH
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