Advanced Fortran Programming 022 Interfacing Functions Video Lecture

hello guys my name is Aaron and welcome
to my channel this series is a series of
tutorials an advanced photon programming
now first of all I like to apologize
because this video comes after quite a
long time
I was actually busy with my thesis and I
had to write a lot of people write a lot
of no make a lot of large and stuff so
it took me it took me a hell lot of time
so I couldn't work on that for quite
some time
so anyway I'm back hopefully for the
next few days I think I be in a position
to know upload more videos as possible
as much as possible ok enough of that
let's get get down to today's work in
this tutorial I will be explaining guys
something about interfacing of functions
and subroutines using the using the
keyword interface the interface
construct available and for that now for
what does what does interface mean
suppose let's say you have a function or
a subroutine in which the variables in
which the variables are different in
different int data type but they do the
exactly the same function for instance
take an example have a look at this
function and this function over here see
this function G underscore term
underscore real okay and what it does is
that it takes a real integer value n
okay and a real type and two real
numbers a not at R and then what it
calculates is that it calculates the
geometric the nth geometric term nth
geometric term of a geometric
progression ok entomophagy are metric
progression and then returns the value
okay
now I'm taking assuming assuming I'm
just thinking clarity of notations I am
assuming the geometric progression
starts with the 0th term so a not as
actually the 0th term and the a n is
actually the N term so that you know the
formula comes neat instead of R or R
power n minus 1 thing is making that the
formula comes neat simple as that
nothing more so ok this
in returns the nth term of a geometric
progression okay but the thing to be
notice is that all the values over here
except for the index which is positive
that's fine all the values over here
there are they are are in you know if
you guys notice all of them are with
real values okay suppose I have a
function where and all these values are
integers along okay now can I can I have
that function yes it does
okay whatever written is I've written
this entire exactly the same function
right over here except that instead of
real I made it int okay and these
variables into a knot and R which are
taken as real values in this function 0
and thus coterminous Kabir I'm taking
them as integers over here other than
that everything else is exactly the same
now the question a question is ok
witness in my in my program do I have a
way okay
so that I can interchangeably call these
functions in without care without
worrying about the datatypes okay see
the problem is this suppose if I have a
four three two four integers and I use
and they use we use a variable to use a
term to invoke one you know invoke this
function okay now can I use the same
name to invoke this function if the data
if the data variables are different and
it's that facility possible let's say if
it's possible the command that make
their lives a little simpler okay
the for the pattern Asst I mean the
third possibility is yes it does exist
now I will explain you guys how that
works okay that's that's this is
possible using this Interphone interface
interface option okay the farm program
the script name is the file name is
entered f90 okay okay now let's go to
into the program part of it okay
what I have here is the program called
as enter which starts here and ends over
here okay i define six seven variables
in total
yes now means this a stands for a
arithmetic
okay nothing much there's a stands for
this the integer first integer custom of
geometric progression in the ratio and
then n n is the number of terms and a
and will have the the nth vomited term
corresponding to these values and mind
you the this all the terms here are
integers similarly I defined the
replicas corresponding values in real
numbers real numbers over here gea 0
stands for the zeroth term of the
geometric progression which is real
similarly G R stands for the geometric
ratio in the real numbers simple as that
GN is equivalent Li the same except that
a in this integer a ga in this DMS real
all right now let's look at how to do
this to make sure that to pass variables
to 2 or any one of these functions with
the same common name okay that that
process is accomplished by this
interface term now what I've done here
is that I do what I've done here is that
I've introduced in to write it on the
keyboard call this interface okay hope
you guys can see this interface and now
what I've given is that I've given the
name Jo underscore term to it so we have
an interface block here whose name is Jo
underskirt tum tum okay and it ends here
and what I've defined here what are
different inside is that I defined the
real function term and the integer
function term inside it nothing what I
defined is that I just defined the
function name function definition and
I'm inside it i define the values the
variables that are being processed
process inside the set of all the
valleys are a process this process
instead use then where you use then you
know process destroyed simple as that
now what I've done similarly I have
returned the same same set of values
into the corresponding to the real term
that the real function giannis
coterminous Coryell inside here and
that's it and what I've done is that in
I just defined only the variable
missions over here whereas the execution
part of it is not included okay and I
can close this interface function here
and now what I am doing is that now I'm
caught now I'm calculating outside this
interface I am calculating the length
geometric term then the downtick term of
a progression or a series whichever you
call it that's not a problem okay here
now aan wilkani in I'm saying that this
is equal to G underskirt term and thence
and I'm passing all the integer
components integer components such as a
knot because this is a integer first
custom of the series an integer this is
the ratio of the terms in the series
that is again in N and N and n is an
integer so that's another problem
similarly I'm using and calling G n with
the same term okay
and with the difference at our variables
but these variables are real except for
this that's integer it has to be integer
except for this these two are real fine
now the thing that's now quite now the
question might arise is that when these
very various values are used which will
this function be used or will this
function be used and similarly when this
term and this line is used
will this be used or will this be used
now the logic the thing here is that
because of this interface function the
giro underscore underscore term will
understated types of these variables
that are being passed into it and since
the since okay passed into it and C's as
to which of these functions that are
interfaced into it have the same who
have the same valve the variables
corresponding to the same corresponding
to the same data types so what it does
is that when this value is passed if
Cara it looks at the data type of a 0a r
and n and k and looks at the
corresponding data types in this
function and in this function if it
looks at this function it will realize
the DA not a zero corresponds to a zero
but it's real but the value defined is
real but this is a not but this is but
this is integer so you'll understand
that okay this is not to be used let's
look at another one and rejects this one
and then it'll go looks here and then if
it looks here what happens is that it
sees this
values integer and this values integer
okay first match and then looks at yeah
it's integer RS integer fine and then n
this integer and then n is integer so we
already have is that we have a full
match over here so it is okay for this
variable I will use this function so
this function and return the value
accordingly now similarly when this is
done what will happen is that this will
reject this function this function
because all of these values are integers
here and will accept this function
because this matches the datatypes
appropriately okay
that's the logic behind it and when that
is used when this call is midnight this
function gets invoked this function get
the real function gets invoked on the
top and it works nicely and the result
is printed out and to make sure that all
these values are printing nicely I'm
just printing out the value of n the
initial term everything over here now
simply put let's since this is a very
simple program just one simple program
we can just execute from genie effect to
compile its compiles fine f9 to build it
builds fine and then fi to execute okay
let me put this in the screen yeah
perfect
now n we are defined to be six so it's
six no problem with that and the a is
zero is one note that there is no
decimal trailing trailing zeros or
decimal points after one and then a rs4
fine which is defined over here and aan
is 4096 now 4000 it is so what does what
it does is that for it is this
multiplied yes but raise the power of 4
to 6 4 power 6 ok so which is 2 power 12
to power 12 10 to power 10 a thousand 24
and to power learn is 2048 to power 12
is 4096 yeah perfect it's right and
similarly it does the same operations
for G for the other part and we have the
decimal trailing zeros over here all
right
now that is it now if we just change the
values over here let's make this 2 and
again this to be this to be 1 okay so go
out to compile build and run this you
see it's you see it's perfect you get
the you get the modifications quite
nicely and it just works out
okay that's uh that's all I have for you
guys in this tutorial this will be very
much useful this interface for option
will be very much useful for functions
and subroutines which have exactly the
same syntax but whose values whose data
types are differing and whose data types
are different for the variables that's
it and this interface has much more lard
more fish a lot more features in the
next tutorial we will see how to
interface functions outer interface
functions and pro-c subroutines that are
inside modules and all okay thank you
guys for watching and I'll see you guys
the next tutorial so together right