Re: IOS floating point performance
Re: IOS floating point performance
- Subject: Re: IOS floating point performance
- From: David Rowland <email@hidden>
- Date: Wed, 07 Aug 2013 15:38:50 -0700
I have written an app that does astronomical calculations like that , Sun and Moon rise and set and location and….. I never saw a problem with speed. I was very impressed with how much it can do. However, are you using Objective C methods for the calculations? The run time dispatch in Objective C could slow things considerably. I wrote all my math in C++.
David
On Aug 7, 2013, at 1:50 PM, Trygve Inda <email@hidden> wrote:
> I have an app that is running slow. I have narrowed it down to several
> functions which are trig-intensive (used to calculate the position of the
> moon at a given moment and more specifically to calculate rise/set times).
>
> To calculate the position and rise/set times for a month on average,
> requires:
>
> 300 trig functions for position
> 24 points in time to find the correct set of three points
> 30 days
> 2 events
>
> Total of 432,000 trig functions (mostly sin and cos)
>
> On my iPad 3, this takes about 3 seconds, and on my desktop (2.3GHz
> Quad-core i7) it is nearly instantaneous.
>
> I am using doubles (not floats).
>
> What can I do to speed this up?
>
>
>
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