println("Hello, World!")

typeof(1 + -2)

typeof(1.2 - 2.3)

π
typeof(π)

typeof(2 + 3im)

typeof("This is Julia")

typeof("π is about 3.1415")

#'Julia symbols provide a way to make human readable unique identifiers.

:my_id
typeof(:my_id)

1 + 1

#'Even math involving complex numbers

(2 + 1im) * (1 - 2im)

sin(2π / 3) == √3 / 2

sin(2π / 3) - √3 / 2

sin(2π / 3) ≈ √3 / 2

1 + 1e-16 == 1

(1 + 1e-16) - 1e-16 == 1 + (1e-16 - 1e-16)

b = [5, 6]

A = [1 2; 3 4]

x = A \ b

A * x

A * x == b

@show b' * b
@show b * b';

t = ("hello", 1.2, :foo)
typeof(t)

t[2]

a, b, c = t
b

t = (word = "hello", num = 1.2, sym = :foo)

t.word

d1 = Dict(1 => "A", 2 => "B", 4 => "D")

d1[2]

Dict("A" => 1, "B" => 2.5, "D" => 2 - 3im)

d2 = Dict("A" => 1, "B" => 2, "D" => Dict(:foo => 3, :bar => 4))
d2["B"]
d2["D"][:foo]

for i in 1:5
    println(i)
end

for i in [1.2, 2.3, 3.4, 4.5, 5.6]
    println(i)
end

for (key, value) in Dict("A" => 1, "B" => 2.5, "D" => 2 - 3im)
    println("$key: $value")
end

i = 10
for i in 0:3:15
    if i < 5
        println("$(i) is less than 5")
    elseif i < 10
        println("$(i) is less than 10")
    else
        if i == 10
            println("the value is 10")
        else
            println("$(i) is bigger than 10")
        end
    end
end

[i for i in 1:5]

[i * j for i in 1:5, j in 5:10]

[i for i in 1:10 if i % 2 == 1]

Dict("$i" => i for i in 1:10 if i % 2 == 1)

function print_hello()
    println("hello")
end
print_hello()

function print_it(x)
    println(x)
end
print_it("hello")
print_it(1.234)
print_it(:my_id)

function print_it(x; prefix = "value:")
    println("$(prefix) $x")
end
print_it(1.234)
print_it(1.234, prefix = "val:")

function mult(x; y = 2.0)
    return x * y
end
mult(4.0)
mult(4.0, y = 5.0)

[1, 5, -2, 7]

[1.0, 5.2, -2.1, 7]

function mutability_example(mutable_type::Vector{Int}, immutable_type::Int)
    mutable_type[1] += 1
    immutable_type += 1
    return
end

mutable_type = [1, 2, 3]
immutable_type = 1

mutability_example(mutable_type, immutable_type)

println("mutable_type: $(mutable_type)")
println("immutable_type: $(immutable_type)")

@show isimmutable([1, 2, 3])
@show isimmutable(1);

using Random
[rand() for i in 1:10]