Benchmark: Powers of two - MeasureThat.net

Tests:

Outside
var p = [1,2,4,8,16,32,64,128,256,512]; for (var n=0;n<10;n++) { var s = (Math.floor(65*0.098)+65)*p[n]; };
Inside
for (var n=0;n<10;n++) { var s = (Math.floor(65*0.098)+65)*Math.pow(2,n); };
Outside with division
var p = [1,2,4,8,16,32,64,128,256,512]; for (var n=0;n<10;n++) { var s = (Math.floor(65/10.24)+65)*p[n]; };
Inside with division
for (var n=0;n<10;n++) { var s = (Math.floor(65/10.24)+65)*Math.pow(2,n); };

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Outside
Inside
Outside with division
Inside with division

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 26 days ago):

LLMs can make mistakes. Check important info.

Let's dive into the provided benchmark definitions and explain what's being tested, compared, and their pros and cons.

**Benchmark Definition**

The benchmark definition is a JSON object that provides metadata about the test case. It contains:

* `Name`: A human-readable name for the benchmark.
* `Description`: A brief description of the test case.
* `Script Preparation Code` and `Html Preparation Code`: These fields are empty, indicating that no setup code is required before running the benchmark.

**Individual Test Cases**

There are four test cases, each representing a different way to calculate powers of two:

1. **Outside**
```javascript
var p = [1,2,4,8,16,32,64,128,256,512];
for (var n=0;n<10;n++) {
    var s = (Math.floor(65*0.098)+65)*p[n];
};
```
In this test case, the power of two is calculated by multiplying the element at index `n` in the array `p` with a scaled value. The calculation is done outside the loop.

2. **Inside**
```javascript
for (var n=0;n<10;n++) {
    var s = (Math.floor(65*0.098)+65)*Math.pow(2,n);
};
```
In this test case, the power of two is calculated using the `Math.pow` function inside a loop.

3. **Outside with division**
```javascript
var p = [1,2,4,8,16,32,64,128,256,512];
for (var n=0;n<10;n++) {
    var s = (Math.floor(65/10.24)+65)*p[n];
};
```
In this test case, the power of two is calculated by dividing a scaled value and multiplying it with an element in the array `p`. The calculation is done outside the loop.

4. **Inside with division**
```javascript
for (var n=0;n<10;n++) {
    var s = (Math.floor(65/10.24)+65)*Math.pow(2,n);
};
```
In this test case, the power of two is calculated using `Math.pow` and a scaled value inside a loop.

**Comparison**

The main difference between these test cases is where the calculation of powers of two is performed: outside the loop (test cases 1 and 3) or inside the loop (test cases 2 and 4).

Pros and Cons:

* **Outside**: This approach can be faster since it only requires a single calculation per iteration. However, it may not be as efficient if the loop has many iterations, as the scaled value needs to be computed once.
* **Inside**: This approach requires more computations per iteration but is generally faster for loops with many iterations. It also avoids the need to store the scaled value.

**Library Usage**

None of the test cases use any external libraries.

**Special JS Features/Syntax**

None of the test cases use any special JavaScript features or syntax (e.g., async/await, Promises).

**Other Alternatives**

Other approaches to calculate powers of two could include:

* Using a binary search algorithm to find the power of two.
* Using a lookup table to store precomputed powers of two.
* Using a hardware-accelerated function like `__builtin_ctz` (for integer logarithm) or `pow` with high precision.

These alternatives may offer better performance or efficiency, but they are not tested in this benchmark.

Latest run results:

Run details: (Test run date: 7 years ago)

User agent: Mozilla/5.0 (Windows NT 6.1; rv:53.0) Gecko/20100101 Firefox/53.0

Browser/OS: Firefox 53 on Windows 7

View result in a separate tab

Test name	Executions per second
Outside	18566682.0 Ops/sec
Inside	11878778.0 Ops/sec
Outside with division	18621244.0 Ops/sec
Inside with division	11797327.0 Ops/sec

Related benchmarks:

Powers of two (version: 0)

If they should be written in an array or in the loop as we go

Comparing performance of: Outside vs Inside vs Outside with division vs Inside with division

Created: 7 years ago by: Guest

Jump to the latest result

Outside

Inside

Outside with division

Inside with division

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 26 days ago):