Advanced Fortran Programming : 005 : Date and time; Random Numbers; Where construct Video Lecture | Introduction to Fortran Programming (AdvancedLevel) - Database Management

hello guys my name is Aaron and welcome
to my channel this series is a series of
tutorials on advanced Fortran
programming now in this video I'll
explain you guys how to do a ver
operation or vas salute var construct
there's available Fortran I'll explain
you guys how to you know get the date
and time from the system using us using
a subroutine in the system and then some
how to generate random numbers I mean
this random number generation will be
very well be like very simple okay
they're all written a programmer over
here it's quite long so I will just walk
I'll walk you guys through okay I define
two variables here two integers here R
and C for defining for defining caller
for defining matrices P at the score n a
logical matrix P underscore n and to ram
address 2 real matrices ran Matt 1 Ranma
- okay and then define the integer
integer and I decided of values array
whose the a loose array which is like 8
units long just eight values and then
there is this integer cases lying
separately and then I have an integer
dimension an integer array called a seed
which is allocatable so I said Saturday
diver I said that the dimension to be
unknown unspecified II I'm not saying
with that mention here we'll come to
know how this works okay now first let's
go to the data date and time operation
see there's an inbuilt subtlety inside
the inside Fortran called a state and
the state underscore and underscore time
what it does is that the it what it does
is that it sends the do does some
internal calculations are measuring
expression except I don't know how
exactly that it does but it returns
values it turns in a 1/8
valued array as the answer
as a subroutine answer okay now this
this violation the right hand side the
left hand side is actually the system
it's actually the subroutine value
whereas this is the value that gets
outputted I mean there's good get out
comes out okay and now I just copied
this from I just copied this from you
know I mean this common statements from
GCC genome photons on online
documentation okay it's like this over
here I will explain you guys what's
happened here values is an internal
variable and then the first value here
will be the year ii will denote the
month the third will dearth of date in
the month then the fourth will denote
the time difference from this current
time zone that i'm right working right
now or you're working right now with the
diff with UTC time or the universal time
I mean UTC time or the Greenwich
Meridian time whatever you call it the
time exactly at the zero zero degrees
longitude okay the time difference
between be in that time zone and your
time zone in minutes minutes the names
it prints the however of the day then
prints the minute of that minute of the
hour and then pin the second of the
minute and then it prints the
milliseconds of the second at whenever
it whenever it's done okay now what I'm
doing is that the with this the dead end
time is over okay now I will work on
with random functions random numbers C
to generate random numbers all you need
is this subroutine call over here that's
it this random underscore number written
inside it takes some values either a
matrix or a number it doesn't matter
it'll generate a random number the
subroutine will do a random number and
stores it inside the matrix and that's
it nothing that's it but the problem is
I don't exactly say it's a problem but
what happens is that when you define
something like this anyway when you
compile this program again and again and
again on a repeated basis
what happens is that you just get the
same random random number again and
again I mean the same set of random
numbers again and I get it again so to
make the random numbers a little
different what I'm doing is that I'm
just doing I'm just implementing a small
set of routines small set of routines
which I kind of browsed through online
now to give courtesy to the Fed to give
gratitude to the person who did this
okay I was searching through some
internet and I found this blog I found
this question and answer session and
Linux questions dark and then the
somebody asked him CL okay he asked a
question like how do I use random
numbers random numbers at random C such
that the random numbers are different
legs every time okay and this person
with this you know login name I suppose
so
sousou's Ariel LD crawl he wrote a small
code here initially I didn't understand
what's going on but I have to know
implement this test it with a few stuff
and got it so I this called I kind of
implemented this call over here Thanks
thanks guys thank you thank you sir
bye thank you sir for your code it kind
of helped so this way I mean I thought
of not acknowledging the person
otherwise if I just blindly copy this
input this will be like this is not this
will not be good right so I thought I'll
acknowledge this person okay coming back
okay what it does
what what what the code actually does is
that it calls this random underscore
seed subroutine okay and assigns the
value size to the value K now what does
this does is that it generates a random
series random series for seed random
series for seeding some sub preceding
some value to generate a random number C
random number is generated generated
like like a sequence in Fortran so what
happens is that when this random
remember us called without having any
any stuff any value put into it then it
just there's a same number same sequence
again and again and again prints the
same sequence again and again now this
stuff is used for altering the sequence
nothing more
now this random seed gives a value for K
okay okay and this case this value K
will be the same all the time because
this K here before before this line
we're not using the random seed again
random underscore seed or subroutine so
this value will remain Asus's so if you
write if you were compiling if you get
something like 14 or something for k
this value 14 will remain the same and
then what it does is here I'm printing
the QL if K and then what I'm doing is
that I'm allocating the seat array on
the top from values 1 to K okay from
Alice 1 to K and then I'm setting the
value of C the value seed value all the
values of seed to the value of 8 now
what this does is that this 8 will that
will actually be the milli second milli
second that will get in this values okay
see if you guys notice the year will
remain same for say me the rear among
the values the year will remain constant
for the next that particular year the
month for next particular 30 days or 28
days or some of depending the day will
remain constant for that particular day
this UTC time differences you know will
remains say will remain constant
as long as you are in the same time zone
are same time zone
ok I'll reveal it will change only when
you change different time zones or some
kind of a catastrophic problem happens
in the world and the time zones get out
is making a fog here anyway this hour
will you know the hour will change once
in every hour you know - same as that
but seconds they'll change but no
problem but milliseconds they'll just
change instantly ok at least for our
understanding at least for our
conceptualization milliseconds change
every instant the program runs so
generate kind of a random value between
0 and 999 okay so we this value is being
fed into this random seed over here and
what this does is that it takes okay
it's it I mean that value 8 is being
stored as all the values of seed here
okay and now I'm printing the seat just
to give what's going on and then I'm
calling this random underscore seed and
using this put variable inside what I'm
doing is that I'm entering the value of
this matrix seed into it thereby now it
will generate an entirely different set
of random number sequences okay and with
this being done with this being done if
I call this random underscore number and
to put ran ran mad one model does is
that will generate I said a generated
matrix of random numbers defined by this
size because it means this function as
this function will random and this
subroutine animat the score number will
generate random numbers and it takes
inputs and an array a 1d array 2-d array
3d array it doesn't matter
I even as even a scalar value it doesn't
matter
ela standards and eternal numbers
according to the size of the input and
it'll just take takes care take care of
it that's it ok and then I'm printing
the the values here I'm printing the
random number ran not one here and I'm
printing the Ranma to here
I'm calling the random number function
to get that to get a new set of random
numbers for Ranma - ok and that's it ok
with this random number part is getting
over and now let's move to the Vasek the
Val construct ok now what does this bar
constant desu is that it's an array
operation array array operating
construct Varon okay this function looks
for a certain condition inside the array
from top to bottom till from all the
indices
now if that certain condition is
achieved met somewhere okay then he can
do we can decide as to what can be done
to other arrays or other arrays or other
you can do something about you can do
something here a based on whether this
condition is met or not this way what he
can do is that this Val statement can be
used as some kind of a masking statement
parent if you have if if in a certain
matrix you have certain values in
certain value certain set of values and
if certain values are like this you can
set them at another matrix whose values
like this I'll give an explained you
guys what I mean here okay in this line
what I'm doing in this line what I'm
doing is that if I find any matrix entry
in R and mat one greater than 0.5 what
I'm doing is that in the in the matrix
Ranma - I am setting that particular
value to be negative okay if this ran if
any if suppose in the third position
suppose in the second row and first
column of bran mat one the value is less
than 0.5 what it does is that in the
corresponding location the second row at
the first column of Ranma to that value
will be made negative so if that if that
value is actually already negative will
be positive if it's positive it will be
negative but just a reminder random
numbers functions always give only a
positive number and a number random
numbers if you want I think negative now
run enormous you may have to work a
little or find some other function that
does it
as of now you just have no these
functions is give only a positive random
numbers okay so what it does is that
this number becomes a negative value
over here and this is not the only
construct available for where you can
use an else we're also making it
completely like a logical matrix of
stuff okay since I define a logical
matrix over here logical methods over
here I'm using that over here now what
I've done what I've done is that if that
now after making this my alteration over
here I'm making a condition if if if you
find the some value in run run grandma
to to be greater than zero okay then
said the matrix P underscore n
those indices to be true okay else said
the remaining if this man
it means indices this well it's not met
with said those indices in P underscore
and to be false so what do you have is
that you just have a matrix that shows
whether which indices are true and which
addresses are false something like a
masking function now this kind of job
this is essentially a masking this kind
of a array operations essentially are a
masking stuff so you can use this for
not only I'm asking you for doing other
distance also that depends on the need
I'm printing the matrixes here you seen
this print underscore mat are to to
print this real lemma matrix and then
printing this math experience underscore
math l2 to print this part to print this
in a logical matrix and now I'm at the
top I'm printing the random matrix
around mat one using the same function
print underscore mat are two okay
and then this value print underscore mat
want to print the values which is a 1d
matrix okay this will be if you guys
want to know how this is done I have
written three separate teams over here
these are essentially the same is
essentially the same what it does is
that it just do just the subroutine it's
just exactly same subroutine we saw in
the previous tutorials to fill the
matricis okay 2d mattresses what I've
done is that I just change the data type
to in this mat r2 to be real okay and
then I said this candy said the farmer a
to be real over here and here the mat
and it's print underscore mat l2 this is
logical L stands for logical see here so
I said this to be logical here and I
return a logical you know a logical
format over here and that's it and here
just integer so I just prove integer so
we used just print underscore madmen
alone with keeping it keeping it to be a
default integer so I said the EDI for
the matters to be integer here and the
right item so
enough nothing more nothing less suppose
if I know let me write this as 6 it may
not go all the way to 6 decimal six more
six places or not okay now that being
said that being said let's execute this
I have written a small shell script to
do the same I'm removing all the modules
object and executed files here
I'm compiling the funk song from
comparing the file building the file to
get an executable running the executable
now there's one advantage in geni
instead of going to the terminal right
now and tunnel right now and executing
this bash bash script and as long as he
made this an executable what you can do
is simple what he can do is simple all
you have to do is that press f5 come
here and press f5 okay that's a little
embarrassing that's a little
embarrassing it should come anyway it
should come okay anyway this isn't
working as good from here yeah anyway
now what it does is that it just prints
everything from the top the most the
file the most files the executables K is
12 okay and it sits it puts seed to be
hung 132 there are 12 values of K the
value of K is 12 so there are 12 values
of the seed if you cannot as 1 2 3 4 5 6
7 8 9 10 9 10 11 12 12 values of seeds
they're all they're all the same
ok and the date is printed as it is and
if you guys compile compile the
conditions over here ok the year is 2015
and today's date is the date a man I
recorded this video it's there it's 2015
and it's May when the month is May and
that's 14 there I'm recording this in
14th me ok and then I'm in India so the
you the time difference between UTC
my time my places fire five hours at 30
minutes so that's 330 minutes and then
when I record this video it's for its 1
p.m. in the afternoon when they run this
it's 1 p.m. in the afternoon after and
post 10 minutes after 4:00 after 1 p.m.
and it exactly ran at 48 seconds and 152
milliseconds so so this is how this
terminology goes here as for the that
date and time function they don't have
support in this concern and then it
prints the random matrix Tran mat one
here okay and the a spur of a wave
function what it does is that if in
these locations these locations to see
the values are less than 0.5 so in these
locations okay
the random matrix initially it's all
positive
but in these locations since these are
less than Z less than 0 these gets
converted into negative because of this
valve construct over here and what what
happens is that now since this is fixed
now this is fixed now using this Rivera
operation over here Vale's concept over
here
wherever the ran mattes greater than 0
greater than 0 this p underscore my and
and matrix is said to be true and
wherever it does false and wherever it
is false it is said to be false wherever
it is less than 0 it is said to be false
all right and if you guys just have a
look at this these are the addresses
like like that now if ever to build this
in a favor to know execute this again
for some reason my the only this is
working and if you guys notice this is
essentially a different set of values
except for this part over here the
Madras is Intel and self in itself is
entirely different but if you guys
remove the seed and all this job and run
the same I'm pretty sure right it'll be
different
ok now I think that's too much
information for
this one tutorials I stopped here I will
in the next tutorial I will come and
explain you guys with some other
interesting topic that will be of
important that we have great importance
thank you guys for watching and see you
guys the next two days so bye and take
care