Julia Quick Note [10] Function (2) Application

Function (2) Application (Example of writing)

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◆ Type specification
　#Argument is Int type(integer)Is specified, and the return value is Float64(Real number)Specify
　function comsumption_tax(price::Int)::Float64
　    tax_rate = 1.08
　    return tax_rate * price
　end

◆ Type specification(One line display)
　comsumption_tax(price::Int)::Float64 = tax_rate * price


◆ Variadic argument
■ Example sentence 1
　　function summation(v...)
　　    total = 0
　　    for i in v
　　        total += v
　　    end
　　    return total
　　end

■ Example sentence 2
　　function summation2(v::Int...)
　　    total = 0
　　    for i = 1:length(v)
　　        total += v[i]
　　    end
　　    return total
　　end


◆ Optional arguments
　#Initial value of argument is set in advance(Below example: Set the initial value of v2 to 100)
　function foptional(v1, v2=100)
　    total = v1 + v2
　    return total
　end


◆ Keyword argument
　#As a delimiter;(semicolon)use(See the commentary below for details)
　function car(length, width; color="white", price=10000)
　    println("special car:")
　    println(" lenth x width = ", length, " x ", width)
　    println(" color = ", color)
　    println(" price = ", price)
　end


◆ Anonymous function
■ Example sentence 1
　　#Only one argument can be specified
　　price = x -> x * 1.08

■ Example sentence 2
　　#If there are multiple lines, enclose them in begin to end.
　　nebiki = x -> begin
　　    price = x * 0.9
　　    return price * 1.08
　　end

Commentary

(1) Type specification

The type is not required, but it can be. By specifying the type, you can create a more rigorous and accurate program.

You can specify the type with only the argument, or you can specify the type with only the return value. Calling a function that does not match the type will result in an error.

(2) Variadic argument

** ◆ Summary ** (1) You can change the number of arguments. (2) Only the last argument can be set. (3) It is not possible to make two or more arguments variable length. (4) Type can be specified for variable length arguments.

** ① You can change the number of arguments. ** ** In the example below, there are one, two, and three arguments. Since the value set in the argument is taken out as a list (array), you can also write the loop part as follows. ** ② Only the last argument can be set. ** ** The following writing is not possible.

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function summation(v..., x)
    ...

** ③ It is not possible to make two or more arguments variable length. ** ** ** ④ You can specify the type for variable length arguments. ** ** To specify the type for variadic arguments, set as follows.

note10

function summation(v::Int...)
    ...

(3) Optional arguments

** ◆ Summary ** (1) The initial value of the argument can be set in advance. (2) Multiple arguments can be specified as options. (3) Write optional arguments together at the end of the argument.

** (1) The initial value of the argument can be set in advance. ** ** If the argument value is omitted, this initial value will be applied. ** ② Multiple arguments can be specified as an option. ** ** ** ③ Write optional arguments together at the end of the argument. ** ** The following writing is not possible.

note10

function foptional(v2=10, v1)
    ...

(4) Keyword argument

** Use this when you want to set the value of a specific argument among multiple arguments. ** ** In the example below, the first two arguments are normal arguments, and the price value is set among multiple arguments. Note that **; ** (semicolon) is used to separate regular and keyword arguments.

(5) Anonymous function

This function is very similar to the arrow function. ** ◆ Summary ** (1) Only one argument can be specified. (2) When defining the processing of multiple lines, enclose it in begin to end.

** ① Only one argument can be specified. ** ** You cannot set multiple arguments. ** ② When defining the processing of multiple lines, enclose it in begin to end. ** ** In the example below, two lines are processed.

Table of contents

Julia Quick Look Note [01] How to use variables and constants Julia Quick Look Note [02] Arithmetic Expressions, Operators [Julia Quick Note [03] Complex Numbers] (https://qiita.com/ttabata/items/225c77a4d71fafc3e482) Julia Quick Look Note [04] Regular Expression [Julia quick note [05] if statement] (https://qiita.com/ttabata/items/4f0bcff1e32f60402dfb) [Julia fast-drawing note [06] loop processing] (https://qiita.com/ttabata/items/2a53825101b0b75fb589) [Julia Quick Note [07] try, catch, finally] (https://qiita.com/ttabata/items/1d6fe990526c99b65b5f) [Julia Quick Look Note [08] Variable Types (Int, Float, Bool, Char, String)] (https://qiita.com/ttabata/items/2b84a826e39bfe432b62) [Julia Quick Look Note [09] Function (1) Basics] (https://qiita.com/ttabata/items/d9b4f2728ec0dbcc6394)

(* We will continue to increase the content)

Related information

: paperclip: Julia --Official page https://julialang.org/

: paperclip: Julia --Japanese official document https://julia-doc-ja.readthedocs.io/ja/latest/index.html

: paperclip: First time Julia and installation (Windows & Linux) https://qiita.com/ttlabo/items/b05bb43d06239f968035

:paperclip: Julia - Mathematics https://docs.julialang.org/en/v1/base/math/

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