Julia在計(jì)算階乘的時(shí)候，如果階乘數(shù)超過(guò)21，便會(huì)出錯(cuò)，但是如果加一個(gè)big()便可以計(jì)算了

julia> factorial(big(21))
51090942171709440000

過(guò)去不知道的一個(gè)小技巧??！
如果需要建立一個(gè)函數(shù)對(duì)應(yīng)的詞典，則先創(chuàng)造一個(gè)詞典，比如通過(guò)

julia> a = Dict(1=>"one",2=>"two")
Dict{Int64,String} with 2 entries:
  2 => "two"
  1 => "one"

對(duì)應(yīng)的此點(diǎn)就有了key和values

julia> keys(a)
Base.KeySet for a Dict{Int64,String} with 2 entries. Keys:
  2
  1
julia> values(a)
Base.ValueIterator for a Dict{Int64,String} with 2 entries. Values:
  "two"
  "one"

詞典建立也可以簡(jiǎn)單循環(huán)創(chuàng)造出詞典，比如計(jì)算正弦角度值

julia> dict = Dict(string(i) => sind(i) for i = 0:5:360)
Dict{String,Float64} with 73 entries:
  "320" => -0.642788
  "65"  => 0.906308
  "155" => 0.422618
  "335" => -0.422618
  "75"  => 0.965926
  "50"  => 0.766044
  "190" => -0.173648
  "270" => -1.0

這樣每一個(gè)計(jì)算的值都有一個(gè)對(duì)應(yīng)的keys，這點(diǎn)非常有用。

編輯一個(gè)計(jì)算shannon-wiener指數(shù)的函數(shù)

a = [25,25,25,25]
swH(a)
return 2

可以的