Comment Comment by desdiv On most modern platforms, the cost of each operation, from smallest to largest, is roughly something like this[0]:1. Bit shifting2. Integer multiplication3. Integer division4. Floating point multiplicationThe trick in the article works because the cost of 1 + 2 is still smaller than 3.Multiplying with the inverse of 19, a floating point number, wouldn't work because 4 is more costly than 3.[0] http://nicolas.limare.net/pro/notes/2014/12/12_arit_speed/ parent desdiv 9 years ago
1. Bit shifting
2. Integer multiplication
3. Integer division
4. Floating point multiplication
The trick in the article works because the cost of 1 + 2 is still smaller than 3.
Multiplying with the inverse of 19, a floating point number, wouldn't work because 4 is more costly than 3.
[0] http://nicolas.limare.net/pro/notes/2014/12/12_arit_speed/