{ "explanation": "The Fast Inverse Square Root algorithm computes 1/√x using bit manipulation and Newton's method.", "original_use": "Used in Quake III Arena for lighting and reflection calculations.", "performance": "Approximately 30x faster than standard floating-point division and square root.", "steps": [ "1. Treat the floating-point number as an integer", "2. Right shift the integer by 1 bit", "3. Subtract from the magic number (0x5f3759df)", "4. Treat the result as a floating-point number", "5. Apply one iteration of Newton's method: y = y * (1.5 - (x2 * y * y))" ], "mathematical_basis": "The algorithm exploits the linear relationship between the logarithm of a number and its floating-point representation.", "magic_number_derivation": "The magic number is derived from the IEEE 754 floating-point format and provides a good initial approximation." }