I ran it in Debug mode which should turn off most optimizations. I ran the loop 100 times and then 200 times. The latter took almost exactly twice the time as the former. The results are saved in instance variables of the C++ class this belongs to.
On Aug 8, 2013, at 12:06 PM, Sandy McGuffog <[email protected]> wrote: > 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]
