Lesson 1.3 The MATLAB Desktop Video Lecture - Introduction to Programming

[Music]
welcome back I hope you didn't have any
trouble getting MATLAB and that you're
ready to start using it so I've got two
matlab desktops open here as you can see
my lab online on top and my installed
version at the bottom and you should
have one desktop open either MATLAB
online or your installed version this is
a good time for me to point out one big
advantage of MATLAB online over any
installed version any computer tool that
you access with your web browser like
MATLAB online will periodically improve
without you having to do anything
one day it looks and behaves like well
this and the next day or the next month
you may open it up and find that it
looks a little different and it's got
some new features and that's a very good
thing with this Auto updating of online
tools you don't have to install anything
and yet you always have the latest and
greatest version a side effect is that
the MATLAB online that you see in this
video might look slightly different from
the MATLAB online that you were running
because you are out there in the future
and I'm stuck back here in March 2018
using R 2018 a but the difference won't
be big unless you're so far in the
future that you're wearing a silver
jumpsuit and people are taking vacations
on the moon the generic name for tools
like these whether they're MATLAB online
or installed MATLAB or Excel or Chrome
or call of duty World War two is
graphical user interface or using the
initials as most programmers do we call
it a GUI spelled GUI and like any decent
GUI as we've seen we can resize it and
move it around on our computer screens
and we can use the mouse and the
keyboard to interact with it inside each
of these two MATLAB GUI zwi see three
sub windows the current folder over here
on the left and each of them the
workspace over on the right and the
command window in the middle which is
labeled down here
in the installed version but is not
labeled up here in MATLAB online for
some reason you can see that the three
column layout is the default for the
installed version and I like that
arrangement but you can move things
around a bit to do that just left-click
the window label and while holding that
left button down drag it somewhere else
say let's drag this current folder
window over here under the workspace and
it'll pop into place and you release the
mouse I hate this setup so I'm gonna put
it right back where I had it there
that's a little too wide let's move that
back over there and this is a little too
wide
mm there just right now I'm happy as
Larry with my setup by the way if you
quit MATLAB and restarted ill remember
were your last layout so you don't have
to keep moving things around every time
okay we've got command windows let's
start commanding we can look at the
other windows later if we left click
anywhere in a command window say up here
in MATLAB on line like this we'll see a
little vertical bar start blinking on
and off just to the right of this pair
of greater-than signs that blinking bar
tells us that MATLAB is ready to receive
a command and that pair of greater-than
signs is matlab's prompt
and what's a prompt well let's look it
up in the textbook and click on glossary
and we see the first definition abstract
class well you can learn about abstract
class toward the end of this book where
we introduced the object-oriented
programming constructs in MATLAB
object-oriented programming is one of
the advanced concepts that we mentioned
that are beyond the scope of the course
let's type prompt into the search bar
there it is there's our definition a
prompt is a symbol or symbols printed by
a program MATLAB is an example to
indicate that it is ready for input from
the user of the program MATLAB uses the
prompt greater than greater than two
input a command you type it on the
keyboard and that blinking bar shows you
where it will appear which is just to
the right of the prompt so you're ready
commander it's time to issue your first
command I don't know about you but I'm
pretty excited and here's the command
that we're gonna give type X space
equals space one space plus space two
and hit return or it might be enter on
your computer all right here we go okay
maybe I built that up a little too much
here let me do the same thing in the
installed version
and let's think what just happened in
each desktop MATLAB created variable
named X calculated one plus two stored
the result which was three and X and
then printed the value of X I should say
lowercase X because if I'd used an
uppercase X that would be a different
variable oh and all those spaces around
the equals sign and the plus sign not
necessary I just included them to make
it look prettier here let's leave all of
them out works the same spaces are used
in MATLAB but they're often not needed
usually you'll find that if you can make
sense of what you typed with or without
spaces than MATLAB can - speaking of
space I don't like all those vertical
spaces between the lines the MATLAB
keeps putting there it does that by
default but we can stop that by giving
this command format compact now let's
type x equals one plus two again and no
wait that's way too much work man I
can't be dealing with typing all kinds
of characters over and over just to get
the same command twice no that's not for
me I'm a man of efficiency instead I'll
just hit the up arrow on my keyboard two
times that pops up the last command I
typed and then the one before that and
now all I have to do is hit enter BAM
and there it is and this time all those
useless screen hogging annoying terrible
horrible no good very bad vertical
spaces are gone when I use that up arrow
to see previous commands MATLAB showed
us it's so-called
command history window the command
history is an extremely handy feature of
the desktop and you'll find yourself
using it a lot and we'll use it in this
course
let's hit the up arrow
and this time we'll click this tiny down
arrow here and select doc when we do
that the command history window is no
longer a pop-up window but is right
there all the time if you look at it and
ended up right over here under the
workspace you can scroll around double
click a command to put it in the command
window where you can hit return to
execute it or you can just drag one over
here to execute it hit return and there
it goes
of course MATLAB online has a command
history too well while we've been
neglecting it up here it is timed out no
problem you just log back in again and
it'll come right back and you can use
the up arrow and run previous commands
and as you can see it remembers the
previous commands from one login to
another there is a difference though
when you hit the up arrow in MATLAB
online only one command appears at a
time not the entire history ok I'll hit
return to execute it look it's still
double spaced and let's fix that there
when you want to see the entire history
in MATLAB online you can click up here
on show history and it appears and a
pop-up window you can move it around
change its size you can't drag and drop
commands but you can double click them
to run them so they're ran that one
there's another one it doesn't change
the spacing and because we've already
used it but I just ran the format
compact again
okay that's it for the command history
but I don't why but before we move on
let's tidy up the command window it's
gotten very cluttered there are buttons
for that in both versions but I like to
type more than click so I'll use the
command to do it see L see clear command
window there I'll do it in the install
version too
that's much better
and I'll undock the command history
undock so both desktops have the same
layout
okay okay it's important to get the
layout you want for efficient
programming and now you know how to
arrange things and how to see the
command history and you know how to use
the format command to change to single
spacing there are many other formats
that you can change also such as the
number of digits that are printed to the
right of the decimal point if you want
to see all the format's that you can
request with the command format or if
you want information about any command
whose name you know you can look it up
via the search documentation field right
up here - right on the top of the MATLAB
desktop you just type in format or
whatever you're looking for and hit
return and up pops a window with
information wherever the word format
shows up we'll look at this more closely
later on
before we go further it's important for
you to know how to regain control of
MATLAB if it's taking too long to
process a command the method is
different in the online and installed
versions we'll start with the online
version first I'm going to give a
command it will take way too long to
complete rnd that's seven zeros my
friend and this command tells MATLAB to
cough up 10 million random numbers okay
I'm gonna hit return and step back whoa
and here they come by the hundreds and
the thousands eventually to millions
well this is getting boring but right
down here look at this little button
says stop let's try clicking that I'll
give it a double click try it again
sometimes I've noticed it takes a couple
of clicks if you've let a lot of stuff
pour out onto your window but that will
stop it that's how you rope throw and
tie this little dogie that's my rodeo
talk shows how cool I am
means that's how you stop MATLAB online
now let's give the same command of the
installed version
returned and here they come
where's the stop button no well you can
look till the cows come home still on
the cowboy theme but you won't find one
partner to stop this version or any
installed version of MATLAB you need to
use a special combination of keys called
control C which is done by holding down
the control key I made you say ctrl on
your computer and while you're holding
it down hit the C key there what's a
little more responsive looks like this
little filly knows who's boss what you
didn't know MATLAB was a female I would
have thought the bigger surprise would
be that it's a horse and if you want to
get off this horse you can quit MATLAB
by typing guess what quit queue uit when
you hit return MATLAB will go away
you can also left-click this some red
dot here up at the top top left which an
X shows up when you get close to it or
if you're on Windows you can click the X
at the top right which turns red when
you get to it hey Apple and Microsoft in
this field a little silly anyway another
method is to click this tiny down arrow
up here at the top right and log out of
the online version MATLAB will ask you
if you really want to leave and you
confirm your choice and you'll be right
back at the login screen but this is no
time to quit we need to get back to our
variable X first I'm going to clear the
screen my type in CLC and
return there I'll do that down here -
okay back to the variable X we call X a
variable because its value can vary but
that value always stays the same until
we assign it a new value like this when
we do that the old value in this case 3
is gone that's not special with MATLAB
every programming language provides
variables like this and manages
locations in the computer's memory to
hold their value in fact the definition
of a variable in computer science is
simply a location in memory that has a
name and a value the form of an
assignment statement in MATLAB and in
almost all computer languages for that
matter is the same as it's been since
1957 when Fortran appeared you typed the
variables name than the equal sign and
then an expression like 1 plus 2 or just
4.7 he bears repeating that when we told
MATLAB to assign 3 in the first place to
X it did not yet exist
that was not a problem because MATLAB
created it right on the spot all you
have to do to get a variable with the
name you wish it to have is to assign a
value to it and the magic Genie MATLAB
will grant your wish this is not true
for Fortran it's not true for C C++ or
Java they require a lot of setup work to
create a variable that's one of the
things that makes MATLAB simple to use
and one of the reasons that molars
students preferred it to Fortran after
he'd invented MATLAB for them 40 years
ago for the sort of programs that are
typically written in C C++ and Java
there are good reasons for requiring all
that setup work but it's a lot easier to
get a program written if you can get
along without it and with MATLAB we can
okay now let's just type our variables
name without assigning at anything this
time I'm going to do it in MATLAB online
only because the installed version
doesn't
exactly the same thing let's set X equal
to 4.7 up here too
and then just hit plain old X this time
MATLAB tells us the value of X it's not
so helpful now but very helpful if
you've given 50 commands since you
assigned a value to X and you can't
remember what the value is again there
may be a bit more going on it might be
obvious MATLAB has just searched its
memory for the variable named X found it
checked its value discovered that it's
4.7 and then printed 4.7 in the command
window now let's ask it to look for
another variable how about say Y oops
red type is never a good thing in MATLAB
I've been programming MATLAB for 20
years and I still get a little sting
when I see one of these red error
messages MATLAB is telling us that Y
doesn't exist
it says undefined functional variable Y
because functions can have names like Y
or x2 and MATLAB thought maybe we were
trying to run a function a function is
simply an operation that happens when
you give its name if you don't believe
me check the book an operation that is
invoked by giving its name the computer
science definition is in contrast to the
mathematical definition which is any
operation that produces a result that
depends only on its input a MATLAB
keyword that introduces the function
declaration in MATLAB zem files so it's
a keyword in MATLAB well in vote whew
fancy and I guess I left out the stuff
about the difference between the
computer science definition and the
mathematical definition but you know who
why do we even need to know about the
mathematical definition in a book about
programming if you asked me whoever
wrote this book is just showing off I
will admit the last thing here about the
MATLAB keywords good to know well we'll
get to that a little later anyway we've
already invoke
to function by giving its name remember
when I typed this the function Rand and
all those numbers came flooding out well
I didn't press return this time
well Rand is a function and we invoked
it by typing its name the name stands
for random in the operation it performs
is to calculate random numbers these two
numbers in parenthesis 10 million and 1
are inputs that the function used to
calculate its output let's erase this
thing for it gives us any more trouble
I'm gonna click left and hold the button
down and sweep over it and hit the
Delete key there however if you just
want one random number instead of 10
million of them you can type this R and
without any inputs gives you one random
number between 0 and 1 there are lots of
handy functions in MATLAB in fact that's
one of its strong points but there's no
function named Y since there's no
function and no variable named Y MATLAB
complained not sure why MATLAB mentions
function before variable maybe it's
alphabetical and by the way let's clear
up any confusion between the word
command and the word function they mean
exactly the same thing in MATLAB it's
documentation doesn't distinguish
between these two synonyms but it uses
the word function more often than it
uses the word command at least in my
experience you may have noticed that
things have been popping up over here in
the workspace in MATLAB the workspace is
the set of variables that we have
available to us you can find the fancy
schmancy definition in the textbook but
you don't need that yet the workspace is
in the online and installed versions
look a little different the online
version gives some extra information
about each variable we'll learn what all
that means later but right now all you
need to know is the name of the variable
and its value and that's there in both
of our
so what is this variable hands well this
is a special MATLAB very well whose name
suggests that it holds the answer and it
does it's created automatically to hold
the results of any calculation that's
not assigned to a variable by the user
and except for the fact that MATLAB
assigns it values automatically it's a
normal variable it's very handy because
if you calculate something don't assign
it to a variable and then you wish you'd
assigned it to a variable say zebra and
all you have to do is this and zebra has
the value point eight one four seven so
we know how to create variables now how
do you delete them there's usually no
reason to delete them but if you want to
reduce the workspace clutter you can do
one of two things you can use the clear
command like this zebra is gone or you
can right-click the variable in the
workspace choose delete and it's gone
note that zebra is pink in this clear
command there's that purple anyway
MATLAB uses purplish pink to mean that
the name zebra is being given to the
command clear instead of the value of
zebra clear is not removing the v from
the variable zebra it's removing the
variable zebra from the workspace that's
confusing forget it the reason for the
color is not that important I brought it
up because you might want to know your
eyes aren't playing tricks on you well a
couple of other things about the command
clear first you can tell it to clear two
or more variables and second if you give
the clear command without telling it
which variables to clear it clears every
variable in the workspace let's create
four variables lions
tigers and bears and one more own hi and
I'll give it the value the sum of those
three variables yes you can use
underscore as part of the variable name
and you can use stupid names there are a
few limitations but almost any name
you'll want to use is okay we'll give
you the rules for names later it's
simple if you're wondering about the
order of the variables in a workspace
its alphabetical and you can reverse the
order by clicking this little arrow here
well upward triangle there so now let's
get rid of two of them with clear lions
and lions and oh I know we got three to
go let's clear them this way clear with
nothing after it gets rid of everything
and they're all gone I'm sure you've
been noticing things popping up while
I'm typing such as this is a list of
functions that start with the letters CL
you see one you want to invoke you can
select it and hit the tab key and it'll
be typed for you like this one and I can
hit return and it'll will do nothing
because it's already clear this is
called tab completion works a bit
differently in the installed version
there you hit the tab key once to pop up
the list and then it's the same here's
another example
this time I typed the name of the
function and a left parenthesis you know
like I'm getting ready to put an input
in there and what pops up it's called a
function hint it reminds me what inputs
I can give this function okay
let's clean up by clearing the command
window this time I'll do it with the
clear commands button up here and let's
do it down here too at first I'll clear
the workspace over here but instead of
using the clear command I'll use clear
workspace and they're gone and now I'll
clear this window and I use clear
commands down here good all tidied up
neat and nice oK we've looked at the
command window and the workspace window
but we haven't looked at the current
folder window over here for both
versions of MATLAB the current folder is
the place where MATLAB saves the files
that contain the programs that you write
and it's the first place it'll look to
find files that hold programs that it
needs to run to learn about the current
folder window let's start up here with
MATLAB online the first question is
where is this folder well for starters
it's not on your computer the current
folder is inside a computer that's
maintained by the math works with space
set aside for your use and only your use
when you got your account login and
password you were instantly allocated
space and given access to it through
this folder the name of the folder is
MATLAB Drive and you can see the name
right here in this white area
which is called the address field we'll
show you in a little bit how you can
copy stuff between your MATLAB Drive and
your computer but for now we'll just
focus on the MATLAB Drive itself this
bar above these three windows is called
the current folder toolbar and we're
going to be looking at everything in it
we've already looked at one thing the
address field and that's this part right
here the name of the current folder is
always shown in the address field the
stuff inside the current folder is
always shown in the current folder
window there's not a lot to begin with
they're just two folders one name
published and one name shared we're not
gonna use these folders but someday you
may find them handy after you've
completed this course as a full fledged
MATLAB programmer and you start working
on shared projects with other people
people anywhere in the world that have
access to the Internet if you want to
learn about these folders and other
things we don't have time to cover in
this introduction you can find some
documents on MATLAB online and the
course resource links well let's put
some things in the current folder the
current folder which is MATLAB and drive
suppose I want to have a folder in there
named first lesson well I come up here
and click this big yellow plus sign and
select folder this little window pops up
and I type the name
and either left click OK or hit the
return key and there it is now I want
you to watch carefully I'm going to
double click my new folder and that will
make it my new current folder I'll
double click on the count of 3 while you
watch the address field 1 2 3 click and
as promised it's name is there in the
address field but why is the previous
current folder MATLAB Drive still there
- well if you can wait a minute I'll
explain it first let's put something in
first lesson I want two folders studying
the textbook and using MATLAB the 2
things you need to do to succeed in this
course I'll do it quickly there now the
current folder window shows that there
are two folders in the current folder
which is first lesson now let's change
our current directory just studying the
textbook remember how you do that just
double click it ok now you can see why
MATLAB Drive was there the address field
shows you the path you would have to go
from the MATLAB Drive which holds
everything to studying the textbook you
have to first go into first lesson and
then into studying the textbook in
computer science terms the folder name
studying the textbook is a so-called
child of first lesson which is its
parent and first lesson is a child
MATLAB Drive you might be tempted to
call studying the textbook the
grandchild of
drive don't nobody says that people will
make fun of you
yeah I'm still scarred by it and no
grandparents either oh and a folder has
just one parent not like you and me we
have two the parent is considered to be
a higher level in the folder hierarchy
than its children siblings are at the
same level and the folder at the highest
level in this case MATLAB Drive is
called the root folder it's hard to
picture the root being at the top
instead of the bottom just picturing
upside down tree that's what I do one
last thing about folders another name
for a folder is a directory and some
MATLAB commands use that terminology in
fact you may hear me occasionally slip
up and call a folder or directory that's
what I was taught to call them when I
first learned about all this stuff using
Unix in 1980
what's Unix well you know just google it
now let's do some stuff with the current
folder in the installed version when
MATLAB started the first time right
after its installation did a couple of
things for me regarding folders first
thing it did was create this folder
named MATLAB as a child of documents
which is a child of Fitz PJM which is a
child of users which is the root folder
you probably figured out from this then
my username is Fitz by JM let's keep
this on the down-low because if it gets
out it might be a security risk stands
for John Michael Fitzpatrick and I just
celebrated st. Patrick's Day which is
well just googling you'll have your own
username there of course the other thing
that happened when MATLAB started is
that it made MATLAB the current
directory oops sorry
it made MATLAB the current folder you
can think of this MATLAB folder is
similar to the MATLAB Drive folder up
here except the disk folder
and all these folders are sitting down
here inside my computer not up in the
cloud
okay so let's put a folder in here I'm
gonna name it lesson 1 instead of first
lesson so we won't get it confused with
a folder up here in the cloud a couple
of ways to add a folder with the
installed version first you can
left-click the tiny down triangle up
here at the top right of the current
folder window and select new folder
second you can right-click inside the
window itself and select new folder
which is the way I like to do it because
it's easier to hit this big window with
a click and that teeny-weeny triangle
now I have a folder named new folder
I'll change its name by right-clicking
it selecting rename and typing the name
I want lesson 1 there and as before I'll
quickly add studying the textbook and
using MATLAB in there
this address field is not just a pretty
place to see the path from the root
folder to the current folder you can use
it to navigate to and it works exactly
the same in each version so I'll
demonstrate it in my lab online if you
let click one of these little triangular
separators like this one you see a list
of the children of the folder to the
left and if you select one of them with
a left click like this it becomes the
current folder and like this
like this and you can left-click any of
the names in the path to go there
back to first lesson and back to MATLAB
drive and over here on the right you can
see a list of recent current folders by
clicking this little down arrow and all
this and if there are too many a scroll
bar will appear over here on the right
so you can see more you can go to any
one of them by clicking on it I'll go to
publish just for fun this is fun right
we're having fun aren't we a little bit
well get ready for even more fun folks
because in case you haven't seen enough
ways to navigate through your folders
we've got four more over here at the far
left into the current folder toolbar is
a so-called back arrow which takes you
to the last current directory before now
which in this case was MATLAB Drive and
when you go back this forward error
lights up this one undoes the back
arrows work frankly I find the forward
arrow to be more confusing than useful
but if I click it now we go back to
published wait clicking forward took us
back to where we were before we clicked
back whoa see is that confusing or what
I just don't use it
just to the right of these two arrows is
a little icon showing a folder with a
microscopic black up arrow on it I'll
hover the mouse over it you'll see its
name up one level so which way is up
well up is toward the parent to the
current folder which as we mentioned is
considered to be higher than its
children as we can see from the address
field the parent of the current folder
is MATLAB Drive so another way to
explain this button is to say that it
moves you to the left one step in the
address field so let's click it
and our current folder becomes MATLAB
Drive both these arrows and the up one
level icon work in exactly the same way
in the installed version always work and
we're right back where we started man
let's get out of here I happen to know
about a hidden door right here it says
little icon of an open folder with a
tiny green arrow curving down we hover
over it we see its name browse for
folder we quick that and what hmm this
pop-up is only partially displays
because my browser window is too small
it's making bigger there oddly the name
of the window is different from the name
of the button it opened it select a new
folder instead of browse for folder but
the idea is the same and it works like
the browser on your computer but a
little slower in MATLAB online it shows
the available file system this folder up
here named MATLAB add-ons comes with the
installation all set up to allow you to
add things that you purchase from the
MATLAB store don't worry you don't have
to purchase anything for this course you
and I are going to build all the things
we need in our own little workshop with
a mouse and a keyboard but if you do
want to buy something you can shop at
the add-on store by clicking up here on
this little stack of red green and blue
blocks and you're at the store the
Browse button for the installed version
works the same way first I'm going on
just things a little bit
yeah the difference with installed
versions browser button is that it opens
the finder on Mac or File Explorer on
Windows or whatever browser your
operating systems happens to provide and
you can navigate to any folder on your
computer and make it the current folder
when you go to MATLAB there like that
okay one last thing on the current
folder toolbar here if you can stand it
hey look if I can stand it you can stand
it okay way over here on the right this
little magnifying glass which is the
universal symbol for search if you click
it and you can type the name of a file
you want to find over here hit return
and it'll look for it in the current
folder and in the children of the
current folder and all their descendants
but we don't have any files to search
for we got folders we got children of
folders what we got in there files let's
create one I'll click this X to end my
file search and then to create a file
I'll use the tool in this gray area up
here we've already sneaked up here and
clicked a thing or two but we haven't
really talked about it the area above
the current folder toolbar is called the
tool strip and it contains so-called
global tabs they're global because
they're always there no matter what
you're doing with MATLAB the Home tab is
on top of the plots tab and apps tab if
I click the plots tab it comes to the
top where we can see it and the same for
the apps tab but we'll spend most of our
time with a home on top let's click the
new script button over here on the left
it's asking for a new script name and
it's already put an extension for the
file name the dot and the M I'm going to
type pretty picture in front of the DA
and click okay a couple of things have
happened first three new global tabs
appeared editor publish and file
versions second a new window appeared
here this is the editor window it's
where we'll type our MATLAB programs
actually instead of programs I should
say more precisely functions we're going
to create functions and then run them by
typing their names in the command window
MATLAB will then run them in this
scenario MATLAB is the program and the
function is part of the program well
you've got it to desktop open MATLAB is
running if you want that program to do
your bidding you write a function and
invoke it giving its name in the command
window you write functions by typing
MATLAB commands into the editor window
and for most of this course that's all
you're gonna do we'll teach you all
about it but right now all I want to do
is paste a function in there that I've
copied from the math works website it
was written by Cleve Moler and Jack
little back in the 1980s I've copied it
and now I'll put my mouse into the
editor window and hit command V which is
done by holding down the command button
while hitting the V key if you're
running MATLAB on a Windows system
instead of the command key you use the
control key now I'll go over here in the
editor window and click this Save button
I just turned blue there we have stored
the MATLAB code that you see in the
editor window into the file name pretty
picture dot M let's stretch the desktop
down a little bit so we can see the
whole function there it's too early in
the course for me to explain how this
function works but I will mention one
thing about it all those lines is start
with a % the ones that are green are
referred to as comments which means
comments to the user of the function
they're not MATLAB commands but they are
important help people understand how the
function works where it came from
and how to use it for example this
comment tells us that we should give the
command an input and that a good input
to use is number 500 now we're ready to
run it we run functions that we've
written in exactly the same way as we
run built-in functions like Rand and
clear and format we type its name and if
it required inputs we add them in
parentheses well that is a pretty
picture I noticed that a new global tab
showed up here in the tool strip named
figure it lets you change the way the
picture is presented but we'll leave it
like it is
well I wonder what would happen if I
changed five hundred to a thousand I'll
hit up arrow click the left arrow on my
keyboard come over here hit delete and
hit one zero and return what about 100
it's interesting how much complexity you
can get out of five lines of MATLAB one
two three four five well six counting
this one up here the comments don't
count because MATLAB doesn't even use
them the COS here by the way means
cosine and si n means sine these are
built in MATLAB functions that are being
invoked by our function
let's change cosine to sine and see what
happens
I'm hit up here and running again
what oh my fault I forgot to save it she
just blew this means we're supposed to
save it first forgetting the scent here
I'll save it forgetting to save changes
before running is a very common human
error at least that's what I keep
telling myself
MATLAB online will save automatically
for you about once a minute but you'll
find that when you're correcting errors
in a function you'll need to save more
often than that the installed version
saves as soon as you click anywhere
outside the editor window so you don't
need to remember to save but with the
online version you need to remember to
do it yourself so I've saved this time
but if you would please remind me to
save next time my memory is not the best
so I'm running again uh para well that's
disappointing
I'll try changing the second one to TA
in for tangent
well it's not bad it's not as boring as
a straight line at least I think I'll
change this sign to tangent to see what
happens here we go oops okay thanks for
reminding me
I would definitely forgotten this time
I'll save it what Barrow again and here
we go with another straight line
okay I've saved several versions of this
file now suppose I want to go back to a
previous version well I can click this
tab labeled file versions click this
down arrow and it shows me how many
versions I've made these are versions I
made while you were watching me these
are ones I've made before as I was
working on this video for you I can pick
any version I want let's pick this one
that's the one we had or I can click
this button named older and go back one
step
I can go newer and go forward one step
and I can click restore is latest and
give whatever version that's in the
editor window at the time the time stamp
right now that's the latest version ok
I've fiddled with changes to this file
just so I could tell you about file
versions and now I am so done with this
function let's close its editor by
clicking this little X right here let's
go over here in the current folder
window click right on this thing and
let's delete it yes I am sure I want to
delete this file because for this
Oh nuts I should have kept this thing in
case I have to reshoot this video well
guess what MATLAB is gonna come to my
rescue you can get deleted files back no
there's no tab for it but there is a
website I'm going to use the URL HTTP
colon slash slash drive dot MATLAB and
you can see I've been there before com
you usually have to log into this just
like you logged into your regular
account but I logged in a few minutes
ago so to save us some time here well
look here there's my MATLAB Drive
there's first less than there's
published it's all here there's no
shared because as I mentioned shared is
not really a proper folder and if I
click this little arrow I get to see
what's inside here but it's all here and
down here at the bottom left we see how
much space we've used 254 kilobytes I
have five gigabytes you'll have only 250
I've got to 5 gigabytes because of a
license
Vanderbilt has but she won't need look
this as one thousandth of 254 megabytes
so you're in good shape but there's
something more important here in this
page than that look over here at this
one deleted files it'll show us the
files that we've deleted since we
started using MATLAB online let's click
that wow I didn't realize I deleted that
much stuff
I do remember this file adsf made it by
accident I think I'll permanently delete
it because I know I'll never need that
to do that I click right on it and pick
permanently the league and of course it
says do you really want it to different
permanently delete folks there's no
coming back from this so yep gone doing
that doesn't affect the space you've
used because deleted files don't count
against your total allotment and
speaking of permanently deleting things
any file that stays in the deleted
folder for 30 days will automatically be
deleted so let's scroll down and look
for the file we want oh there it is
pretty picture to restore it a couple
ways you can click restore up here or
you can click right and choose restore
and then that reassuring pretty picture
restored to MATLAB Drive go to location
I'm just going to click here and there
it is okay let's move this up a little
bit I'd like to have the same function
in my installed version from MATLAB
pretty picture I could click new script
in the Home tab which will open up the
editor wind and do all the things we did
before and MATLAB online but that would
be repetitious and more importantly
there is a much easier way now that
we've got the pretty picture file ready
to go I'm gonna download the file from
the cloud onto my computer first I
highlight the file by left clicking it
then I click this download button
in the Home tab
what happens then depends on the way
you've set up your browser I mind set up
to download things to my download folder
so I'm gonna look there I open up finder
go into downloads and folks there it is
pretty picture and that's down here on
my computer it showed up here at the top
because I keep my downloads folder
organized so that the latest things are
at the top and I'm gonna copy it go to
my MATLAB folder which I also have in
favorites navigate to using MATLAB and
move it there there we go now let's come
down here let's look in there using
MATLAB there it is and we're ready to
run it let's do that
and there it is but in the installed
version it appears in a floating window
instead of being docked inside the
desktop oh it looks even better when
it's bigger reverting to an earlier
version of a file and restoring a
deleted file is not a built-in part of
installed MATLAB there are lots of
third-party options for that though I
use Dropbox professional which provides
it and believe me it has saved me more
than once
okay I'm gonna clear things up let's
make this a little bit smaller let's get
rid of this bar showing downloaded files
by clicking this X over here on the
right
there I can pull this down a little bit
okay so that's how you get earlier
versions and undelete files in MATLAB
online okay we just downloaded a file
from the MATLAB online cloud to my
computer now let's upload one from my
computer to the cloud nothing can be
easier
first I find the file I want in my
finder here's what I want this JPEG file
I could use the upload button up here
but I prefer to left-click the file hold
down the left button and drag it over
here to the current folder and there it
is and maybe you'd like to see the
picture in this file
well that's also easy with MATLAB you
can type the built in function M show
and give it an input of the name of the
file
notice that I put the file name inside
single quotes hmm the mayor is that a
little small let's make it bigger
that's a little bit better you can read
all about making and displaying images
with MATLAB in the textbook just look up
image processing in the glossary and
click the blue link at the bottom of the
page
all this uploading and downloading can
be automated MathWorks provides a tool
called the MATLAB Drive connector that
will continually synchronize the files
in your MATLAB drive with a folder on
your computer when you change something
in one place it's changed in the other
when you add a folder or a file or
delete something it happens in both
places you can find out how to get it
done in the resource section of this
course
what are we learned in this video well
lots of stuff we've learned how to use
the folder and file system we've learned
how to write and run a function and we
learn how to use the command window the
workspace and the command history and
these things are gonna go in very handy
in the next video well as we gaze at
this beautiful aqueduct in the South of
France and as we perhaps wish that we
were there or in my case wish that I was
back there again well in this video get
in our time machine and return to those
early days in the fall of 2014 and I
explained how you could use MATLAB as a
calculator a very powerful calculator
I'll see you 4 years ago
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