Re: [Boost-users] [chrono] float-based milliseconds?

Subject: Re: [Boost-users] [chrono] float-based milliseconds?
From: Michael Powell (mwpowellhtx_at_[hidden])
Date: 2013-08-31 06:26:03

On Sat, Aug 31, 2013 at 4:06 AM, Vicente J. Botet Escriba
<vicente.botet_at_[hidden]> wrote:
> Le 31/08/13 01:26, Michael Powell a écrit :
>
>> Hello,
>>
>> Or any of the chrono-steady-clock-based time units...
>>
>> I am noticing some what appear to be rounding errors outputting
>> resulting millisecond values using the boost::chrono::milliseconds(x).
>>
>> It's a design-decision, most if not all of our floating-point values
>> are single-precision-float, don't need to be double-precision-float.
>>
>> When we output the milliseconds(x).count() values, however, what I am
>> finding is that the values are sometimes inaccurate, the same value in
>> 3.0, for instance, output as 2.99995, stuff like this.
>
> Please, could you provide an example an the output you are getting?
>
>
> Is there a way to tell milliseconds what precision floating point it
> is? float or double?
>
> I don't see yet where the double is playing on
>
>     typedef duration<boost::int_least64_t, milli> milliseconds;  // at least
> 45 bits needed
>
> Which version are you using, V1 or V2?

That's a good question, I don't know. I am including
<boost/chrono.hpp>, and using boost::chrono::milliseconds,
boost::chrono::high_resolution_clock::now to source my
stopwatch/stopwatchelapsedtimer concept.

>>
>> We are targeting ARM, BTW, without hardware floating point support,
>> which is the main reason, I'd like to keep things single-precision
>> float, if at all possible.
>>
>>
> Vicente
>
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