How to ensure accuracy in golang

In computer science, precise decimal calculations are a common problem because when using binary to represent decimals in computers, some decimals may not be able to represent exact decimal numbers in binary. This leads to the problem of rounding errors when processing decimals in computer programs, which are amplified in scenarios with high computational complexity. Therefore, modern programming languages ​​provide some methods to deal with decimals, one of which is to use the decimal type. In this article, we will explore how to use decimal types in Go.

What is the Decimal type

The Decimal type is a high-precision decimal type that can represent precise decimal values ​​and can perform various arithmetic operations. The Decimal type is usually passed into a computer program as a string and then converted to a Decimal type for calculation. In Go, the Decimal type is provided by the built-in package big.

How to use the Decimal type

In Go, we can use types to represent decimal numbers. Use functions to convert strings to Decimal type. For example, the following code converts the string "123.45" to the Decimal type:

import "math/big"
 
func main() {
    d := ("123.45")
    (d)
}

This program will output 123.45. We can also use the() method to convert the Decimal type to a string.

import "math/big"
 
func main() {
    d := ("123.45")
    (())
}

This program will output a 123.45 string.

Decimal type arithmetic operation

The Decimal type supports various arithmetic operations such as addition, subtraction, multiplication, and division. Here is an example of arithmetic operations using the Decimal type:

import (
    "fmt"
    "math/big"
)
 
func main() {
    a := ("123.45")
    b := ("67.89")
    c := ("2")
 
    // Addition    d := new()
    (a, b)
    (d) // 191.34
 
    // Subtraction    e := new()
    (a, b)
    (e) // 55.56
 
    // Multiplication    f := new()
    (a, c)
    (f) // 246.90
 
    // Division    g := new()
    (a, c)
    (g) // 61.725
}

In the above code, we first create three variables a, b and c of Decimal type, representing 123.45, 67.89 and 2, respectively. Then we add a and b using the Add method, subtract a and b using the Sub method, multiply a and c using the Mul method, and divide a by c using the Quo method.

Comparison operation of Decimal type

The Decimal type also supports comparison operations, such as equality, greater than, less than, greater than or equal to, and less than or equal to. Here is an example of a comparison operation using the Decimal type:

import (
    "fmt"
    "math/big"
)
 
func main() {
    a := ("123.45")
    b := ("67.89")
 
    // Equal    ((a)) // 0
    ((b)) // 1
 
    // Greater than    ((b)) // true
 
    // Small    ((b)) // false
 
    // Greater than or equal to    ((b)) // true
 
    // Less than or equal to    ((b)) // false
}

In the above code, we use the Cmp method to compare a and a and b. The Cmp method returns -1, 0 or 1, which means less than, equal to or greater than, respectively. We also use the GreaterThan method to compare a and b to determine whether a is greater than b. Similarly, we also use the LessThan method to determine whether a is less than b, use the GreaterThanOrEqual method to determine whether a is greater than or equal to b, and use the LessThanOrEqual method to determine whether a is less than or equal to b.

Formatted output of Decimal type

The Decimal type can be formatted using standard formatted strings. For example, we can format strings using %s to output a string representation of Decimal type. Here is an example of formatting output using standard formatted strings:

import (
    "fmt"
    "math/big"
)
 
func main() {
    a := ("123.45")
    b := ("67.89")
 
    ("a = %s\n", a)
    ("b = %s\n", b)
}

In the above code, we use %s to format the string representation of a and b.

Decimal type precision and rounding

The Decimal type supports custom precision and rounding modes. In Go, you can use the type of Context member to set the precision and rounding mode. Here is an example using custom precision and rounding mode:

import (
    "fmt"
    "math/big"
)
 
func main() {
    a := ("123.4567")
 
    // Create a context object    ctx := new()
 
    // Set the accuracy to two decimal places     = 2
 
    // Set rounding mode to rounding     = 
 
    // Round a    b, _ := (a)
 
    (b) // 123.46
}

In the above code, we create a context object and set its precision to two decimal places. We then set the rounding mode to round and round a. Finally, we output the rounded result.

Summarize

In this article, we explore how to handle Decimal types in Go. We first introduce types in Go and demonstrate how to create and initialize variables of Decimal type. We then introduce how to use the Decimal type to perform basic arithmetic operations such as addition, subtraction, multiplication, and division. We also describe how to use the Decimal type for comparison operations, such as equality, greater than, less than, greater than or equal to, and less than or equal to. Finally, we introduce how to format the output value of the Decimal type and demonstrate how to customize the precision and rounding mode of the Decimal type.

In handling finance, currency, and other scenarios where high-precision calculations are required, the use of the Decimal type can avoid calculation errors due to floating point accuracy errors. In Go, types provide good support for high-precision calculations, allowing us to perform precise calculations conveniently. However, it should be noted that when performing high-precision calculations, the calculation speed is slow and users need to make choices based on actual conditions. At the same time, when using the Decimal type, you also need to pay attention to its accuracy and rounding mode to avoid calculation errors.

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