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POTensor Product Algorithm Optimization
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copied!<pre><code>double data[12] = {1, z, z^2, z^3, 1, y, y^2, y^3, 1, x, x^2, x^3}; double result[64] = {1, z, z^2, z^3, y, zy, (z^2)y, (z^3)y, y^2, z(y^2), (z^2)(y^2), (z^3)(y^2), y^3, z(y^3), (z^2)(y^3), (z^3)(y^3), x, zx, (z^2)x, (z^3)x, yx, zyx, (z^2)yx, (z^3)yx, (y^2)x, z(y^2)x, (z^2)(y^2)x, (z^3)(y^2)x, (y^3)x, z(y^3)x, (z^2)(y^3)x, (z^3)(y^3)x, x^2, z(x^2), (z^2)(x^2), (z^3)(x^2), y(x^2), zy(x^2), (z^2)y(x^2), (z^3)y(x^2), (y^2)(x^2), z(y^2)(x^2), (z^2)(y^2)(x^2), (z^3)(y^2)(x^2), (y^3)(x^2), z(y^3)(x^2), (z^2)(y^3)(x^2), (z^3)(y^3)(x^2), x^3, z(x^3), (z^2)(x^3), (z^3)(x^3), y(x^3), zy(x^3), (z^2)y(x^3), (z^3)y(x^3), (y^2)(x^3), z(y^2)(x^3), (z^2)(y^2)(x^3), (z^3)(y^2)(x^3), (y^3)(x^3), z(y^3)(x^3), (z^2)(y^3)(x^3), (z^3)(y^3)(x^3)}; </code></pre> <ul> <li>What is the fastest (fewest executions) to produce <strong>result</strong> given <strong>data</strong>? Assume, that <strong>data</strong> is variable in size, but always a factor of 4 (e.g., 4, 8, 12, etc.).</li> <li>No Boost. I am trying to keep my dependencies small. STL Algorithms are ok.</li> <li>HINT: result array size should always be 4^(multiple size) (e.g., 4, 16, 64, etc.).</li> <li>BONUS: If you can compute <strong>result</strong> just given x, y, z</li> </ul> <p>Additional examples:</p> <pre><code>double data[4] = {1, z, z^2, z^3}; double result[4] = {1, z, z^2, z^3}; double data[8] = {1, z, z^2, z^3, 1, y, y^2, y^3}; double result[16] = { ... }; </code></pre> <p><strong>I chose the accepted answer code after running this benchmark: <a href="https://gist.github.com/1232406" rel="nofollow">https://gist.github.com/1232406</a>. Basically, the top two codes were run and the one with the smallest execution time won.</strong></p>

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