David,

Those are lightening speeds. So I agree with you wholeheartedly -- there is no 
sense in working on a custom table-driven approach. The current approach must 
already be table-based with speeds like that.

Tom Wetmore


On Aug 8, 2013, at 1:26 PM, David Rowland <[email protected]> wrote:

> I wrote an app that calculates the positions of Sun and Moon and other 
> information as well. The heart of the Moon calculation is this. I added a 
> loop around it and called a stopwatch at the beginning and end.
> 
>   startTime();
>   for (int jj = 0; jj<100;++jj)
>   {
>   //in radians
>   double lambda = 3.81040282295402 + 8399.70910754626 * T
>   + 0.109781209950443 * sin(adjustValueRadians(2.35619449019234 + 
> 8328.69146829639 * T))
>   - 0.022165681500328 * sin(adjustValueRadians(4.5256387504213 - 
> 7214.06294691607 * T))
> 
> One hundred times through this loop, on my iPhone 5, took about 0.0028 
> seconds. Two hundred times took about 0.0056 sec.
> 
> I infer that one pass takes about 0.000028 seconds, or 28.0 microseconds.
> 
> The functions are probably very carefully written and could not be improved 
> by table lookups, vector libraries, etc. That is barking up the wrong tree. 
> 
> David

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