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    <p>Does it take around 15 seconds to do anything 160000 times for you? Benchmark it on your system just returning x; it may well be that the hypot operation ( implemented in C ) is negligible than the interpreter overhead.</p> <p>For ruby 1.8.7 with khell's memoized get method, calling the function inside a get method, and just returning x inside a get method, with 100000 iterations:</p> <pre> peregrino:$ time ruby src/memoized_hypot.rb real 0m1.714s user 0m1.436s sys 0m0.080s peregrino:$ time ruby src/plain_hypot.rb real 0m0.495s user 0m0.364s sys 0m0.060s peregrino:$ time ruby src/empty_hypo.rb real 0m0.369s user 0m0.220s sys 0m0.068s </pre> <p>kheill's memoization creates a string on every call, which is much more costly than calling the C library's hypot function on every call. </p> <p>The difference between the calling hypot and just returning x indicates that hypot is only contributing 25% of the runtime. It's not the code you should be optimising - instead try inlining the call to the library if you can rather than wrapping it in another method.</p> <pre> peregrino:$ time ruby src/inline_hypot.rb real 0m0.365s user 0m0.236s sys 0m0.044s </pre> <p>which is </p> <pre><code>100000.times{ |i| Math.hypot(i,6) } </code></pre> <p>rather than</p> <pre><code>100000.times{ |i| foo.get(i,6) } </code></pre> <p>where foo is an object with the methods posted.</p> <hr> <p>These times were on a netbook ( Asus eeepc 900 ) which isn't massively speedy, so it's a bit odd that they are much faster than your times. So something else might be dominating your results. </p>
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    1. USPete Kirkham
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    1. CO+1 - never optimize before determining where the code actually spends its time.
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      1. USSarah Mei
    2. COI second Sarah's statement. I just wanted to use native memoization instead of creating a new one.
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      1. USkhelll
    3. COI agree with Sarah's statement. I knew that but I thought that I would be clever anyway. Not a clever move. And your breakdown makes perfect sense so I'm marking it as the answer. I'm too new with ruby, I need to play with it a bit more until I can judge it properly. Still, Thankyou.
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      1. USRobert Massaioli
 

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