Mark Dickinson mdickinson
mdickinson
/ sqrt_exact.c
Last active
November 16, 2024 04:24
Fast square root of a 64-bit square number
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| // Exact square root of a known square integer | |
| // =========================================== | |
| // This snippet contains a function `isqrt64_exact` with signature | |
| // | |
| // uint32_t isqrt64_exact(uint64_t n); | |
| // | |
| // `isqrt64_exact` computes the 32-bit square root of its unsigned 64-bit | |
| // integer input, under the assumption that that input is a perfect square. | |
| // | |
| // Compile under gcc or clang with: |
mdickinson
/ hilbert_curve.py
Last active
October 30, 2015 08:38
Code to create the third-order approximation to a 3d space-filling Hilbert curve
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| import numpy | |
| def hilbert(): | |
| """ | |
| Return NumPy array of shape (512, 3) containing successive coordinates | |
| for a third-order three-dimensional Hilbert curve. | |
| """ | |
| a,b,c=numpy.indices((8,)*3).reshape(3,-1) | |
| d=c[:8];r=abs(d-3>>1);g=(d^d>>1)*73;f=g[abs(d-1)&6] |