A branch instruction is not inherently slower than any other instruction. However, the reason you heard that branches should avoided is because modern CPUs follow a pipeline architecture. This means that there are multiple sequential instructions being executed simultaneously. But the pipeline can only be fully utilised if it’s able to read the next instruction … Read more
I believe the approach is to actually use a 3 dimensional noise field (every point in a 3D space has a scalar noise value) as opposed to a 2 dimensional field (every point on a 2D plane has a noise value). When using a 2D noise function to generate a height map, you offset the … Read more
Not being a regex expert, but finding the problem interesting, I looked around and found this interesting blog entry. Especially the syntax used there for defining the 2D regex looks appealing. The paper linked there might tell you more than me. Update from comment: Here is the link to the primary author’s page where you … Read more
Here’s my own solution, based on the idea in ask Dr. Math. I’d be happy to see your feedback. Disclaimer first. This solution is correct for spheres. Earth isn’t a sphere, and the coordinates system (WGS 84) doesn’t assume it’s a sphere. So this is just an approximation, and I can’t really estimate is error. … Read more
Try this one: (n >> 1) ^ (-(n & 1)) Edit: I’m posting some sample code for verification: #include <stdio.h> int main() { unsigned int n; int r; for(n = 0; n < 10; n++) { r = (n >> 1) ^ (-(n & 1)); printf(“%u => %d\n”, n, r); } return 0; } I … Read more
As long as it changes whenever the resource representation changes, how you produce it is completely up to you. You should try to produce it in a way that additionally: doesn’t require you to re-compute it on each conditional GET, and doesn’t change if the resource content hasn’t changed Using hashes of content can cause … Read more
The key to these large-number modulus tasks is not to compute the full result before performing the modulus. You should reduce the modulus in the intermediate steps to keep the number small: 500! / 20! = 21 * 22 * 23 * … * 500 21 * 22 * 23 * 24 * 25 * … Read more
ratio = MIN( maxWidth / width, maxHeight/ height ); width = ratio * width; height = ratio * height; Make sure all divides are floating-point.
Perl, 99 characters @P=map{$/.substr$”.’__/ \\’x99,$_,$W||=1+3*pop}0,(3,6)x pop; chop$P[0-$W%2];print” __”x($W/6),@P Last edit: Saved one character replacing -($W%2) with 0-$W%2 (thanks A. Rex) Explanation: For width W and height H, the output is 2+2 * H lines long and 3 * W+1 characters wide, with a lot of repetition in the middle of the output. For convenience, we … Read more
Here are a few approaches. I’ll (try to) illustrate these examples with a representation of a 3×3 grid. The flat array +—+—+—+—+—+—+—+—+—+ | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | +—+—+—+—+—+—+—+—+—+ a[row*width + column] To access elements on the left or right, subtract or … Read more