Strength reduction is a program optimization technique that replaces more expensive operations with cheaper ones.
A few examples of strength reduction:
| Expensive operation | Cheaper operation | |
|---|---|---|
| Division by a power of 2 | a / 2**n |
a >> n |
| Modulo by a power of 2 | a % 2**n |
a & (2**n - 1) |
Replacement of pow |
pow(a, 0.5) |
sqrt(a) |
pow(a, 1.5) |
a * sqrt(a) |
|
pow(a, -1.5) |
1.0 / (a * sqrt(a)) |