I don’t remember last time I implemented sorting, search or trees, these are available in all languages and runtimes.
Skill, I implement a lot of my own algorithms. Following reasons.
1. Performance. Custom algorithms and data structures is often a requirement to write performant code, because SIMD, memory hierarchy, and other modern hardware-related shenanigans largely ignored by authors of standard libraries.
2. GPGPU. Due to their massively parallel nature they need completely different algorithms, a naïve implementation is often by an order of magnitude slower than purposely built one, due to things like memory access coalescing and group shared memory.
3. Licensing. In my area of work (CAD/CAM/CAE) some good quality libraries are only available as GPL or even AGPL. Apparently, the commercial licenses are targeted towards companies like GM or Airbus, way too expensive.
Skill, I implement a lot of my own algorithms. Following reasons.
1. Performance. Custom algorithms and data structures is often a requirement to write performant code, because SIMD, memory hierarchy, and other modern hardware-related shenanigans largely ignored by authors of standard libraries.
2. GPGPU. Due to their massively parallel nature they need completely different algorithms, a naïve implementation is often by an order of magnitude slower than purposely built one, due to things like memory access coalescing and group shared memory.
3. Licensing. In my area of work (CAD/CAM/CAE) some good quality libraries are only available as GPL or even AGPL. Apparently, the commercial licenses are targeted towards companies like GM or Airbus, way too expensive.