Be careful using that code as a test; a good optimizing compiler could pick up that sin is a library function without side effects, and no result is saved, and optimize that loop to two calls to adjustValueRadians.
Sandy On Aug 8, 2013, at 8:17 PM, Thomas Wetmore <[email protected]> wrote: > 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 > > _______________________________________________ > > Cocoa-dev mailing list ([email protected]) > > Please do not post admin requests or moderator comments to the list. > Contact the moderators at cocoa-dev-admins(at)lists.apple.com > > Help/Unsubscribe/Update your Subscription: > https://lists.apple.com/mailman/options/cocoa-dev/mcguffogl%40gmail.com > > This email sent to [email protected] _______________________________________________ Cocoa-dev mailing list ([email protected]) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to [email protected]
