High-precision calculations and related functions in PHP

PHP is a very popular server-side programming language. It is not only easy to learn and use, but also provides a wealth of built-in functions and extensions, which is very suitable for processing various types of data. One of them is high-precision calculation. This article will introduce high-precision calculation and its related functions in PHP.

1. What is high-precision calculation

In computers, data is usually stored in binary form, so the size of a number is limited by the data type. For example, a 32-bit integer type can only represent a maximum of $2. ^{31}-1$, when exceeding this range, overflow will occur. However, some applications need to process very large values, such as encryption algorithms, cryptography, scientific computing and other fields, in which case high-precision calculations are required.

High-precision calculation is a numerical calculation method implemented through software. It can process more numbers than the number of digits supported by the hardware, and has the advantages of high precision, high reliability, and high accuracy. Strings are usually used to store numbers and perform mathematical operations such as addition, subtraction, multiplication, and division to achieve high-precision calculations.

2. High-precision calculations in PHP

PHP provides a built-in BC mathematics extension, which can achieve high-precision calculations and support numerical calculations of any length. The BC math extension needs to be loaded at runtime and can be loaded by setting extension=bc.so in the php.ini file. The following are some common functions of BC mathematics extension:

1. bcadd() function: performs high-precision addition operations and returns higher-precision operation results.
2. bcsub() function: performs high-precision subtraction operations and returns higher-precision operation results.
3. bcmul() function: performs high-precision multiplication operations and returns higher-precision operation results.
4. bcdiv() function: performs high-precision division operations and returns higher-precision operation results.
5. bcpow() function: performs high-precision power operations and returns higher-precision operation results.
6. bcsqrt() function: performs high-precision square root operations and returns higher-precision operation results.
7. bccomp() function: Compares the size of two high-precision numbers and returns 0, 1 or -1.
8. bcmod() function: performs high-precision modulo operation and returns higher-precision operation results.

In addition to the BC mathematics extension, PHP also provides the GMP extension, which can achieve higher-precision numerical calculations and support calculations of more than 500,000 digits. The GMP extension also needs to be loaded at runtime and can be loaded by setting extension=gmp.so in the php.ini file. The following are some common functions of GMP extensions:

1. gmp_add() function: performs high-precision addition operations and returns higher-precision operation results.
2. gmp_sub() function: performs high-precision subtraction operations and returns higher-precision operation results.
3. gmp_mul() function: performs high-precision multiplication operations and returns higher-precision operation results.
4. gmp_div() function: performs high-precision division operations and returns higher-precision operation results.
5. gmp_pow() function: performs high-precision power operations and returns higher-precision operation results.
6. gmp_mod() function: performs high-precision modulo operation and returns higher-precision operation results.

3. Application Example

The following is an example of practical application of high-precision calculation, multiplying two larger decimal numbers:

$num1 = "12345678901234567890";
$num2 = "98765432109876543210";
$result = bcmul($num1, $num2);
echo $result; // 1219326311370217954807669063466076789910

above In the code, first define two larger numbers $num1 and $num2, then use the bcmul() function to multiply them, and finally output the operation result.

4. Summary

High-precision calculation is a very practical numerical calculation method that can meet the needs of many applications. PHP provides built-in BC math extensions and GMP extensions, which can achieve high-precision calculations. You need to pay attention to the format and accuracy of the data when using it to avoid errors.

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