Benchmark: Quake InvertSqrt

Script Preparation code:

var i;
var r;
var v = 2**16;

function test1() {
  for(i=0; i < 1000; ++i) {
    r = Math.sqrt(v);
  }
}

function test2() {
  for(i=0; i < 1000; ++i) {
    r = Q_rsqrt(v) * v;
  }
}

const bytes = new ArrayBuffer(Float32Array.BYTES_PER_ELEMENT);
const floatView = new Float32Array(bytes);
const intView = new Uint32Array(bytes);
const threehalfs = 1.5;

function Q_rsqrt(number) {
  const x2 = number * 0.5;
  floatView[0] = number;
  intView[0] = 0x5f3759df - ( intView[0] >> 1 );
  let y = floatView[0];
  y = y * ( threehalfs - ( x2 * y * y ) );

  return y;
}

Tests:

Math.sqrt
test1()
Quake InvertSqrt
test2()

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Math.sqrt
Quake InvertSqrt

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: one year ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/133.0.0.0 Safari/537.36 Edg/133.0.0.0

Browser/OS: Chrome 133 on Windows

View result in a separate tab

Test name	Executions per second
Math.sqrt	677609.2 Ops/sec
Quake InvertSqrt	53540.7 Ops/sec

Autogenerated LLM Summary (model llama3.2:3b, generated one year ago):

LLMs can make mistakes. Check important info.

Let's break down the provided benchmark and explain what is being tested.

**Benchmark Definition**

The benchmark definition json contains two test cases:

1. `test1()`: This function calls `Math.sqrt(v)` 1000 times, where `v` is initialized to a power of 2 (2^16).
2. `test2()`: This function calls the custom `Q_rsqrt` function, which is an implementation of the Quake Invert Sqrt algorithm. The input `number` is also initialized to a power of 2 (2^16).

**Options being compared**

The two test cases are comparing the performance of:

* Using JavaScript's built-in `Math.sqrt` function
* Using the custom Quake Invert Sqrt algorithm implemented in `Q_rsqrt`

**Pros and Cons**

* **Built-in Math.sqrt**: Pros:
	+ Well-maintained and widely supported by browsers.
	+ Typically faster due to optimized implementation.
Cons:
	+ May use more memory or have more complex code.
* **Quake Invert Sqrt algorithm**: Pros:
	+ Can be faster than built-in `Math.sqrt` for certain inputs.
	+ May require less memory.
Cons:
	+ Less well-maintained and supported by browsers.
	+ Requires custom implementation.

**Library usage**

The test case using the Quake Invert Sqrt algorithm uses a library called "Quake". Quake is a vectorized math library that provides optimized implementations for various mathematical operations, including inverse square root. The `Q_rsqrt` function in the benchmark definition is an example of this library's implementation.

**Special JS feature/syntax**

There are no special JavaScript features or syntax used in these benchmarks. They only use standard JavaScript functions and data types.

**Other alternatives**

If you're interested in testing alternative methods for calculating inverse square roots, you could consider using:

* The `v8::math` library (available in the Chromium source code) which provides a similar implementation to Quake.
* Other custom implementations or libraries that provide optimized inverse square root functions.
* Using approximation techniques, such as Taylor series expansion, to calculate inverse square roots.

Keep in mind that these alternatives might not be directly comparable to the built-in `Math.sqrt` function or the Quake Invert Sqrt algorithm, and may require additional considerations for performance, memory usage, and code complexity.

Related benchmarks:

Quake InvertSqrt (version: 0)

Comparing performance of: Math.sqrt vs Quake InvertSqrt

Created: 7 years ago by: Guest

Jump to the latest result

Math.sqrt

Quake InvertSqrt

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated one year ago):