From 1b716e337a763870ec771d29a74b2ff74095bbd6 Mon Sep 17 00:00:00 2001
From: br86redu <br86redu@idiv.de>
Date: Thu, 7 Feb 2019 11:16:38 +0100
Subject: [PATCH] add cheatsheet

---
 FirstSteps.jl | 155 ++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 155 insertions(+)
 create mode 100644 FirstSteps.jl

diff --git a/FirstSteps.jl b/FirstSteps.jl
new file mode 100644
index 0000000..671f95f
--- /dev/null
+++ b/FirstSteps.jl
@@ -0,0 +1,155 @@
+"""
+Setting a working directory with abc
+"""
+cd("/home/Wherever/You/Want") # Linux
+cd("C:\\Users\\Nickname\\Just\\put\\it\\there") # Windows
+"""
+Show the working directory
+"""
+pwd()
+
+"""
+Save your files with a .jl to make atom recognize that its Julia
+and make the colour formatting appear
+"""
+
+"""
+Documentation
+Any string appearing at the top-level right before an object
+is interpreted as documentation (Markdown)
+"""
+# This is a comment :)
+
+"""
+type ? in the REPL to switch to the help menu
+type ; in the REPL to switch to the shell
+type ] in the REPL to switch to the package management
+    ]st     # status of the packages
+    ]update
+    ]add "Plots"
+
+or you can do it like this
+"""
+import Pkg
+Pkg.add("StatsBase") # add the package
+using StatsBase # load the package
+
+Pkg.add("Distributions") # add the package
+using Distributions # load the package
+
+"""
+The define operator is =
+To use the unicode math symbols (e.g. Greek) type \alpha and press Tab
+You cannot redefine a built-in constant or function
+"""
+pi
+a,b,c = 1,2,3
+x = 3
+z = x + a
+z1 = 2x^2 - 3x + 1
+z2 = 2^2x
+x += 1
+d = rand() # choose a random number between 0 and 1
+# randn(10) 10 random numbers- normal distributed
+
+### "===" compare the number and the type of a variable
+
+"""
+Define an array
+"""
+a = [x,y,z] #Array
+b = rand(1:10,6)
+b = rand(2,2) #2×2 Array{Float64,2}
+a = Array{Float64,1} # Array{T,N} N-dimensional dense array with elements of type T.
+# N can be Any, Float64, Int64, String
+# T can be 1 - Vector, 2 - Matrix, 3 - Array
+c = Vector{Float64}(undef,6) # create a vector with random numbers (undefined, row, column)
+c = fill!(c,3)
+d = fill(rand(1:10), (5,5))
+
+g = [1:10;] #create a vector
+g[9] = -9 # change number at pos. 9
+g[3:5] = fill!(g[3:5], -8)
+
+print(g)
+length(g)
+size(b)
+println("text"^2)
+
+"""
+Arithmetic Operators
+(+) (-) (/) (*) (^) (%) (\)
+For every binary operation there is a "dot"-operation that
+    automatically performs element-by-element on arrays
+"""
+x = 3
+-x #mathematical inverse
++x
+y % x # remainder
+x += 3 # is like x = x + 3
++(1,2,3)
+*(1,2,3,4)
+a = [1,2,3]
+b = a .+ 1
+c = a .^2
+
+"""
+build-in mathematical functions
+"""
+Random.seed!(123) # Setting the seed; using Random, Distributions
+d = Normal() #Normal distribution std=1
+x = rand(d,2)
+
+g = [1,2,3,4,5,6,7,8,9]
+sum(g)
+mean(g) # in the Pkg StatsBase
+maximum(g)
+extrema(g)
+
+"""
+- Numeric comparison
+- (==) (!=) (<=) ...
+"""
+x = 3
+x < 5 ? "yes" : "no"
+x = 7
+x < 5 ? "yes" : "no"
+
+# Boolean operators
+x > 5 && "Cool!"
+x < 5 && "Cool!"
+x > 5 || "Cool!"
+x < 5 || "Cool!"
+
+# Loop and if-else statments
+for i in 1:length(g)
+  println("Hallo World ($i)"^2)
+end
+
+name = "Brinkley"
+if name == "Jeeves"
+    println("Very Good Jeeves")
+elseif name == "Brinkley"
+    println("Thank you, Brinkley")
+    println("and shut the door behind you")
+else
+    println("Fine, just ignore me")
+end
+
+"""
+functions in julia
+"""
+# one-line function
+myfunc(value) = 20*value
+myfunc(20)
+# more complicated functions
+function First(x, y)
+    x + y
+end
+First(3,4)
+
+function Sec(x, y)
+    return x*y
+    x + y
+end
+Sec(3,4)
-- 
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