No, they aren’t the same algorithm. For starters, the LINQ OrderBy is documented as stable (i.e. if two items have the same Name, they’ll appear in their original order). It also depends on whether you buffer the query vs iterate it several times (LINQ-to-Objects, unless you buffer the result, will re-order per foreach). For the … Read more
You have two variables here, m and n, where m is the length of the input and n is the number of items in the hash. The O(1) lookup performance claim makes at least two assumptions: Your objects can be equality compared in O(1) time. There will be few hash collisions. If your objects are … Read more
I think it is more concise and understandable to describe the performance characteristics of each panel than it is to try to give an absolute relative performance comparison. WPF makes two passes when rendering content: Measure and Arrange. Each panel has different performance characteristics for each of these two passes. The performance of the measure … Read more
The compiler can’t generally transform for (int c = 0; c < arraySize; ++c) if (data[c] >= 128) for (int i = 0; i < 100000; ++i) sum += data[c]; into for (int c = 0; c < arraySize; ++c) if (data[c] >= 128) sum += 100000 * data[c]; because the latter could lead to … Read more
MongoDB concatenates the compound key in some way and uses it as the key in a BTree. When finding single items – The order of the nodes in the tree is irrelevant. If you are returning a range of nodes – The elements close to each other will be down the same branches of the … Read more
There are two parts to that answer (I wrote it). One part is easy to quantify, the other is more empirical. Hardware Constraints: This is the easy to quantify part. Appendix F of the current CUDA programming guide lists a number of hard limits which limit how many threads per block a kernel launch can … Read more
TL;DR The actual speed difference is closer to 70% (or more) once a lot of the overhead is removed, for Python 2. Object creation is not at fault. Neither method creates a new object, as one-character strings are cached. The difference is unobvious, but is likely created from a greater number of checks on string … Read more
Actually, console.log is a lot slower than an empty function. Running this jsPerf test on my Chrome 38 gives stunning results: when the browser console is closed, calling console.log is about 10 000 times slower than calling an empty function, and when the console is open, calling it is as much as 100 000 times … Read more
A simple possibility that comes to mind is to keep a compressed array of 2 bits per value for the common cases, and a separated 4 byte per value (24 bit for original element index, 8 bit for actual value, so (idx << 8) | value)) sorted array for the other ones. When you look … Read more
Is it really true? and if so does anyone know why? In ancient days, when computers were still chipped out of fused silica by hand, when 8-bit microcontrollers roamed the Earth, and when your teacher was young (or your teacher’s teacher was young), there was a common machine instruction called decrement and skip if zero … Read more