Analyzing Golang floating point inaccuracies

Golang is a very popular programming language. Its simplicity, efficiency, security and other characteristics lay the foundation for its application in cloud computing, containerization, blockchain and other fields. Although Golang has a history of ten years, there are some problems with the processing of floating point numbers. This article will analyze the inaccuracy of Golang floating point numbers.

First, we need to know how floating point numbers are stored. Golang uses 64-bit double-precision floating-point numbers (ie float64) at the bottom level to store floating-point numbers, where part of the binary digits represents the decimal digits, and part of the binary digits represents the integer digits. Due to the limited precision of the computer's internal binary storage of floating-point numbers, only limited binary numbers can be used to approximately represent irrational real numbers, so there is a rounding error.

For example, if we represent 0.1 in binary form, we can get 0.0001 1001 1001 1001..., but due to rounding errors, what is actually stored inside the computer is 0.0001 1001 1001 1001 1001 1001 1001 1010..., This leads to some strange results when Golang handles 0.1.

The following is a piece of Golang code that uses a for loop to output the first 10 decimal places of 0.1:

package main

import "fmt"

func main() {
    var n float64 = 0.1
    for i := 0; i < 10; i++ {
        fmt.Println(n)
        n += 0.1
    }
}

The output we expect is:

0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1

However, in fact, the output The result is:

0.1
0.2
0.30000000000000004
0.4
0.5
0.6
0.7
0.7999999999999999
0.8999999999999999
0.9999999999999999

Obviously, Golang is not able to accurately handle 0.1, but results like 0.30000000000000004 and 0.79999999999999999 appear. This is because inside the computer, 0.1 is approximately represented as an infinite loop of binary numbers. Every time an addition operation is performed, the rounding error will be amplified, eventually leading to asymptotic errors.

In addition to addition operations, Golang's other floating-point operations, such as subtraction, multiplication, division, etc., also have accuracy issues. In addition, overflow or underflow may also occur when dealing with very large or very small floating point numbers.

In order to avoid these problems, you can use the math/big package provided by Golang to handle large numbers and high-precision floating point numbers. In addition, for some application scenarios that require very precise requirements, you can consider using programming languages ​​such as C or Python to implement them.

In summary, Golang will have some inaccuracies when processing floating point numbers, which is caused by rounding errors within the computer. In order to avoid these problems, it is necessary to select appropriate development languages ​​and libraries according to specific application scenarios to ensure the accuracy of calculation results.

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