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    <p>Modern Intel/AMD processors have instruction <code>FSINCOS</code> for calculating sine and cosine functions simultaneously. If you need strong optimization, perhaps you should use it.</p> <p>Here is a small example: <a href="http://home.broadpark.no/~alein/fsincos.html" rel="noreferrer">http://home.broadpark.no/~alein/fsincos.html</a></p> <p>Here is another example (for MSVC): <a href="http://www.codeguru.com/forum/showthread.php?t=328669" rel="noreferrer">http://www.codeguru.com/forum/showthread.php?t=328669</a></p> <p>Here is yet another example (with gcc): <a href="http://www.allegro.cc/forums/thread/588470" rel="noreferrer">http://www.allegro.cc/forums/thread/588470</a></p> <p>Hope one of them helps. (I didn't use this instruction myself, sorry.)</p> <p>As they are supported on processor level, I expect them to be way much faster than table lookups.</p> <p>Edit:<br> <a href="http://en.wikipedia.org/wiki/X86_instruction_listings" rel="noreferrer">Wikipedia</a> suggests that <code>FSINCOS</code> was added at 387 processors, so you can hardly find a processor which doesn't support it.</p> <p>Edit:<br> <a href="http://developer.intel.com/Assets/PDF/manual/248966.pdf" rel="noreferrer">Intel's documentation</a> states that <code>FSINCOS</code> is just about 5 times slower than <code>FDIV</code> (i.e., floating point division).</p> <p>Edit:<br> Please note that not all modern compilers optimize calculation of sine and cosine into a call to <code>FSINCOS</code>. In particular, my VS 2008 didn't do it that way.</p> <p>Edit:<br> The first example link is dead, but there is <a href="http://web.archive.org/web/20100729204636/http://home.broadpark.no/~alein/fsincos.html" rel="noreferrer">still a version at the Wayback Machine</a>.</p>
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    1. POWhat is the fastest way to compute sin and cos together?
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    1. CODo you have any reference for this or a snippet how to call it in C or C#?
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    2. COAre compilers smart enough to use this instruction in case you write: x=cos(a);y=sin(a); That would be great.
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      1. USphkahler
    3. CO@phkahler: That would be great. Don't know if such optimization is used by the modern compilers.
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