Benchmark: Fast Sqrt 2234234

Script Preparation code:

var i;
var r;
var v = 2**16;

function test1() {
  for(i=0; i < 1000; ++i) {
    r = 1 / Math.sqrt(v);
  }
}

function test2() {
  for(i=0; i < 1000; ++i) {
    r = Q_rsqrt(v);
  }
}

//Based on the fast inverse square root function
// https://en.wikipedia.org/wiki/Fast_inverse_square_root
// Some original comments preserved for humor value
// Designed to try to mimic the original as closely as possible
function Q_rsqrt(number)
{ 
    var i;
    var x2, y;
    const threehalfs = 1.5;
  
    x2 = number * 0.5;
    y = number;
    //evil floating bit level hacking
    var buf = new ArrayBuffer(4);
    (new Float32Array(buf))[0] = number;
    i =  (new Uint32Array(buf))[0];
    i = (0x5f3759df - (i >> 1)); //What the fuck?
    (new Uint32Array(buf))[0] = i;
    y = (new Float32Array(buf))[0];
    y  = y * ( threehalfs - ( x2 * y * y ) );   // 1st iteration
//  y  = y * ( threehalfs - ( x2 * y * y ) );   // 2nd iteration, this can be removed

    return y;
}

Tests:

Math.sqrt
test1();
Quakes fast inverse sqrt.
test2();

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Math.sqrt
Quakes fast inverse sqrt.

Fastest: N/A

Slowest: N/A

Latest run results:

No previous run results

This benchmark does not have any results yet. Be the first one to run it!

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

LLMs can make mistakes. Check important info.

Let's dive into the world of JavaScript microbenchmarks on MeasureThat.net.

**Benchmark Definition**

The provided JSON represents a benchmark definition for a JavaScript function called `Fast Sqrt 2234234`. This function is designed to compare two implementations of fast inverse square root calculations, specifically:

1. The built-in `Math.sqrt` method.
2. A custom implementation named "Quakes fast inverse sqrt." (also referred to as `Q_rsqrt`).

The benchmark measures the performance difference between these two approaches.

**Options Compared**

The main options being compared are:

* **Built-in Math.sqrt**: This is the standard JavaScript method for calculating square roots.
* **Quakes fast inverse sqrt. (Q_rsqrt)**: A custom implementation of fast inverse square root, which is designed to mimic the original algorithm from Wikipedia.

**Pros and Cons**

Here's a brief analysis of each approach:

1. **Built-in Math.sqrt**:
	* Pros:
		+ Wide support across browsers and platforms.
		+ Easy to use and understand.
	* Cons:
		+ May not be optimized for performance, leading to slower execution times.
2. **Quakes fast inverse sqrt. (Q_rsqrt)**:
	* Pros:
		+ Optimized for performance, potentially reducing execution times.
		+ Can provide a more accurate result than the built-in method.
	* Cons:
		+ Requires manual implementation and understanding of the algorithm.
		+ May not be compatible with all browsers or platforms.

**Library: Quakes**

The `Q_rsqrt` function is implemented in JavaScript, but it relies on some mathematical tricks and bit-level manipulation. The library used for this implementation is not explicitly stated, but it's likely a custom-built library optimized for performance.

**Special JS Feature/Syntax**

This benchmark uses some special JavaScript features, such as:

* Bit-level manipulation (e.g., `0x5f3759df - (i >> 1)`).
* Floating-point arithmetic (e.g., `(new Float32Array(buf))[0] = number;`).

These features are specific to the implementation and may not be widely supported or understood.

**Other Alternatives**

If you're interested in exploring other approaches, here are a few alternatives:

* **SSE instructions**: Some implementations use SSE (Streaming SIMD Extensions) instructions for optimized performance on x86 architectures.
* **AVX instructions**: Similar to SSE, AVX (Advanced Vector Extensions) instructions can be used for even faster performance on modern CPUs.
* **Native libraries**: You can also consider using native libraries like Eigen or Armadillo for more efficient linear algebra operations.

Keep in mind that implementing these alternatives will require a good understanding of low-level computer science and programming expertise.

I hope this explanation helps you understand the basics of the JavaScript microbenchmark on MeasureThat.net!

Related benchmarks:

Fast Sqrt 2234234 (version: 0)

Compare Quakes fast inverse squareroot

Comparing performance of: Math.sqrt vs Quakes fast inverse sqrt.

Created: 5 years ago by: Guest

Jump to the latest result

Math.sqrt

Quakes fast inverse sqrt.

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

No previous run results

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