# function to calculate the volume of a sphere
function sphere_vol(r)
  # julia allows Unicode names (in UTF-8 encoding)
  # so either "pi" or the symbol π can be used
  return 4/3*pi*r^3
end

# functions can also be defined more succinctly
quadratic(a, sqr_term, b) = (-b + sqr_term) / 2a

# calculates x for 0 = a*x^2+b*x+c, arguments types can be defined in function definitions
function quadratic2(a::Float64, b::Float64, c::Float64)
  # unlike other languages 2a is equivalent to 2*a
  # a^2 is used instead of a**2 or pow(a,2)
  sqr_term = sqrt(b^2-4a*c)
  r1 = quadratic(a, sqr_term, b)
  r2 = quadratic(a, -sqr_term, b)
  # multiple values can be returned from a function using tuples
  # if the return keyword is omitted, the last term is returned
  r1, r2
end

vol = sphere_vol(3)
# @printf allows number formatting but does not automatically append the \n to statements, see below
using Printf
@printf "volume = %0.3f\n" vol 
#> volume = 113.097

quad1, quad2 = quadratic2(2.0, -2.0, -12.0)
println("result 1: ", quad1)
#> result 1: 3.0
println("result 2: ", quad2)
#> result 2: -2.0