Benchmark: Comparing performance of Math.floor(x); vs Math.round(x); vs (0.5 + x) << 0;

Script Preparation code:

var x = Math.random() * 100000000;
var y;

Tests:

Math.floor(x);
y=Math.floor(x);
Math.round(x)
y=Math.round(x)
(0.5 + x) << 0;
y=(0.5 + x) << 0;

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Math.floor(x);
Math.round(x)
(0.5 + x) << 0;

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 2 years ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:122.0) Gecko/20100101 Firefox/122.0

Browser/OS: Firefox 122 on Windows

View result in a separate tab

Test name	Executions per second
Math.floor(x);	349444768.0 Ops/sec
Math.round(x)	352376544.0 Ops/sec
(0.5 + x) << 0;	347423904.0 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's being tested.

**Benchmark Description**

The website MeasureThat.net provides a platform for users to create and run JavaScript microbenchmarks. The current benchmark is designed to compare the performance of three different ways to round a number:

1. `Math.floor(x)`
2. `Math.round(x)`
3. `(0.5 + x) << 0`

**Options Compared**

The benchmark tests the performance of each option by modifying the JavaScript code as follows:

* For `Math.floor(x)`, the code is simply `y = Math.floor(x);`.
* For `Math.round(x)`, the code is `y = Math.round(x);`.
* For `(0.5 + x) << 0`, the code is `y = (0.5 + x) << 0;`.

**Pros and Cons of Each Approach**

1. **Math.floor(x)**:
	* Pros: Simple, efficient, and widely supported.
	* Cons: Can result in truncation errors if the input value is not an integer.
2. **Math.round(x)**:
	* Pros: More precise than `Math.floor(x)` and handles fractional inputs correctly.
	* Cons: Can be slower due to the rounding operation.
3. **(0.5 + x) << 0**:
	* Pros: Can produce a slightly faster result than `Math.round(x)`, as it uses a bitwise shift instead of a rounding operation.
	* Cons: Requires careful handling of edge cases, such as overflow and underflow.

**Library Used**

The benchmark does not explicitly mention any libraries. However, the use of `Math` functions suggests that the JavaScript implementation is standard.

**Special JS Feature or Syntax**

None mentioned in this specific benchmark.

**Other Considerations**

When implementing these options, developers should be aware of potential edge cases, such as:

* Integer overflow/underflow for `(0.5 + x) << 0`
* Fractional input handling for `Math.round(x)`
* Truncation errors for `Math.floor(x)`

**Alternative Approaches**

If the benchmark's goal is to compare rounding performance with additional features, consider the following alternatives:

1. **Decimal arithmetic**: Use a decimal library (e.g., Decimal.js) to round numbers with precise control over rounding modes and precision.
2. **Fuzzy matching**: Implement fuzzy matching algorithms (e.g., Levenshtein distance) for `Math.round(x)` or `(0.5 + x) << 0` to compare floating-point numbers with tolerance.
3. **Approximation methods**: Use approximation techniques, such as Taylor series expansion or binary search, to improve the performance of rounding operations.

Keep in mind that these alternatives may introduce additional complexity and trade-offs, so choose them only if necessary for your specific use case.

Related benchmarks:

Comparing performance of Math.floor(x); vs Math.round(x); vs (0.5 + x) << 0; (version: 0)

Comparing performance of: Math.floor(x); vs Math.round(x) vs (0.5 + x) << 0;

Created: 3 years ago by: Guest

Jump to the latest result

Math.floor(x);

Math.round(x)

(0.5 + x) << 0;

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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