Basics

Installation

Modern Approach: Web

go to https://juliabox.com , enjoy :-) (google or github account requred)
go to https://iam.syzygy.ca , enjoy :-) (github account required)

Less Modern: IDE

Juno http://junolab.org/
Jupyter http://jupyter.org/

Old School: Terminal FTW

install CLI
use your favorite editor (vim, emacs)
(optional) install syntax highlighting
enjoy

Data Types

Defining Variables



In [30]:

    
local x::Bool = true









    Out[30]:





true



In [33]:

    
let
    local x::Bool = 2
end









    



InexactError()

Stacktrace:
 [1] convert(::Type{Bool}, ::Int64) at ./bool.jl:7

Boolean



In [7]:

    
x = true; typeof(x)









    Out[7]:





Bool



In [8]:

    
1 < 2









    Out[8]:





true



In [11]:

    
# Chaining of (in)equalities is possible
1 < 2 == 2 > 0









    Out[11]:





true

Numeric



In [2]:

    
x = 1; typeof(x)









    Out[2]:





Int64



In [3]:

    
x = 1.0; typeof(x)









    Out[3]:





Float64



In [6]:

    
x = 1.0 + 1.0im; typeof(x)









    Out[6]:





Complex{Float64}



In [12]:

    
x = 1 + 1im; typeof(x)









    Out[12]:





Complex{Int64}



In [4]:

    
x = 2//3; typeof(x)









    Out[4]:





Rational{Int64}

Strings



In [20]:

    
x = "Foo"; typeof(x)









    Out[20]:





String



In [17]:

    
y = 'F'; typeof(y)









    Out[17]:





Char



In [24]:

    
x * "Bar"









    Out[24]:





"FooBar"

Basic Operations

Numeric



In [35]:

    
1 + 2









    Out[35]:





3



In [36]:

    
1 - 2









    Out[36]:





-1



In [37]:

    
1 / 2









    Out[37]:





0.5



In [38]:

    
1 * 2









    Out[38]:





2



In [42]:

    
5 % 2









    Out[42]:





1



In [44]:

    
sin(2)









    Out[44]:





0.9092974268256817



In [46]:

    
log(1)









    Out[46]:





0.0



In [48]:

    
exp(1)









    Out[48]:





2.718281828459045



In [51]:

    
sqrt(3)









    Out[51]:





1.7320508075688772

String

Concatenation



In [53]:

    
"Foo" * "Bar"









    Out[53]:





"FooBar"



In [54]:

    
x = 1.0; "x = $(x)"









    Out[54]:





"x = 1.0"



In [56]:

    
"x + 1 = $(x + 1)"









    Out[56]:





"x + 1 = 2.0"

Modification



In [57]:

    
split("Euler,Gauss,Newton",",")









    Out[57]:





3-element Array{SubString{String},1}:
 "Euler" 
 "Gauss" 
 "Newton"



In [60]:

    
strip(" Julia   
               ")









    Out[60]:





"Julia"



In [61]:

    
replace("This is soooo lame!","lame","cool")









    Out[61]:





"This is soooo cool!"

Regular Expression



In [89]:

    
re = r"x=\d+"; typeof(re)









    Out[89]:





Regex



In [90]:

    
ismatch(re,"It might be true, that x=123 and y=4;")









    Out[90]:





true



In [91]:

    
ismatch(re,"It might be true, that x>0 and y=4;")









    Out[91]:





false



In [1]:

    
replace( "x=1.0; y=2.123; z=2",
        r"y=(\d+)(\.?\d?)"    ,
        s"y1=\1; y2=0\2"      )









    Out[1]:





"x=1.0; y1=2; y2=0.123; z=2"

Excercises

Task 1

Install/Open Julia using one of the mentioned options.

Task 2

Calculate the solution of $$x - 10 + e^\pi = \sin(2.5)$$

Task 3

Calculate the exact value of y for $$ y = \frac13 + \frac35 + \frac57 + \frac{7}{11} + \frac{11}{13} $$ and convert the exact value to a floating point number.

Task 4

Create a string according to the following template and replace any occurence of '?' with the appropriate value.

"For x = 4.2 it holds that $\sin(x/2*\pi)$ = ? and $\cos(x/3*\pi)$ = ?"

Task 5

We picked up the following encrypted message from a super secret agency who must not be named.

"Whc1atzcd,th3mc1and5zcc1anzc1ac1an5w,th3r,zc1abc1utzcc1a5k5zcn,thozc1aqc1u,th35t,thi,thon5?"

Fortunately we recently aquired the instructions how to decipher the message. The required steps have to be performed in the given order and are as follows:

convert numbers to letters
- 1 -> l, 3 -> e, 5 -> s
- remove all remaining numbers
remove n letters in front of vowels with n being:
- 2 for a,u
- 3 for o,e,i
replace za and zc with spaces

Decipher the message.

Hint: r"[aou]" matches the vowels a,o or u. r".{3}" matches any three characters.



In [15]:

    
riddle = replace("What demands an  answer,  but asks no  questions?","  ","za")
riddle = replace(riddle," ","zc")
riddle = replace(riddle,r"([au])",s"cl\1")
riddle = replace(riddle,r"([oei])",s"nth\1")
riddle = replace(riddle,"l","1")
riddle = replace(riddle,"e","3")
riddle = replace(riddle,"s","5")
display(riddle)
riddle = replace(riddle,"1","l")
riddle = replace(riddle,"3","e")
riddle = replace(riddle,"5","s")
riddle = replace(riddle,r".{2}([au])",s"\1")
riddle = replace(riddle,r".{3}([oei])",s"\1")
riddle = replace(riddle,r"z[ac]"," ")









    





"Whc1atzcdnth3mc1and5zcc1anzc1ac1an5wnth3r,zc1abc1utzcc1a5k5zcnnthozc1aqc1unth35tnthinthon5?"






    Out[15]:





"What demands an answer, but asks no questions?"

Task 6

Find a string for which the regular expression r"bb|[^b]{2}" matches.

Bonus: What does this regular expression actually mean?