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When you compare this example with a PVM implementation of the same problem, you can see some of the contrasts between the two approaches. Programmers who wrote the same six lines of code over and over in PVM combined them into a single call in MPI. In MPI, you can think “data parallel” and express your program in a more data-parallel fashion.

In some ways, MPI feels less like assembly language than PVM. However, MPI does take a little getting used to when compared to PVM. The concept of a Cartesian communicator may seem foreign at first, but with understanding, it becomes a flexible and powerful tool.

Heat in mpi using broadcast/gather

One style of parallel programming that we have not yet seen is the broadcast/gather style. Not all applications can be naturally solved using this style of programming. However, if an application can use this approach effectively, the amount of modification that is required to make a code run in a message-passing environment is minimal.

Applications that most benefit from this approach generally do a lot of computation using some small amount of shared information. One requirement is that one complete copy of the “shared” information must fit in each of the processes.

If we keep our grid size small enough, we can actually program our heat flow application using this approach. This is almost certainly a less efficient implementation than any of the earlier implementations of this problem because the core computation is so simple. However, if the core computations were more complex and needed access to values farther than one unit away, this might be a good approach.

The data structures are simpler for this approach and, actually, are no different than the single-process FORTRAN 90 or HPF versions. We will allocate a complete RED and BLACK array in every process:


PROGRAM MHEAT INCLUDE ’mpif.h’INCLUDE ’mpef.h’ INTEGER ROWS,COLSPARAMETER(MAXTIME=200) PARAMETER(ROWS=200,COLS=200)DOUBLE PRECISION RED(0:ROWS+1,0:COLS+1),BLACK(0:ROWS+1,0:COLS+1)

We need fewer variables for the MPI calls because we aren’t creating a communicator. We simply use the default communicator MPI_COMM_WORLD . We start up our processes, and find the size and rank of our process group:


INTEGER INUM,NPROC,IERR,SRC,DEST,TAG INTEGER S,E,LS,LE,MYLENINTEGER STATUS(MPI_STATUS_SIZE) INTEGER I,R,CINTEGER TICK,MAXTIME CHARACTER*30 FNAMEPRINT *,’Calling MPI_INIT’CALL MPI_INIT( IERR ) CALL MPI_COMM_SIZE( MPI_COMM_WORLD, NPROC, IERR )CALL MPI_COMM_RANK( MPI_COMM_WORLD, INUM, IERR) CALL MPE_DECOMP1D(COLS, NPROC, INUM, S, E, IERR)PRINT *,’My Share ’, INUM, NPROC, S, E

Since we are broadcasting initial values to all of the processes, we only have to set things up on the master process:


* Start ColdIF ( INUM.EQ.0 ) THEN DO C=0,COLS+1DO R=0,ROWS+1 BLACK(R,C) = 0.0ENDDO ENDDOENDIF

As we run the time steps (again with no synchronization), we set the persistent heat sources directly. Since the shape of the data structure is the same in the master and all other processes, we can use the real array coordinates rather than mapping them as with the previous examples. We could skip the persistent settings on the nonmaster processes, but it doesn’t hurt to do it on all processes:

Questions & Answers

are nano particles real
Missy Reply
yeah
Joseph
Hello, if I study Physics teacher in bachelor, can I study Nanotechnology in master?
Lale Reply
no can't
Lohitha
where we get a research paper on Nano chemistry....?
Maira Reply
nanopartical of organic/inorganic / physical chemistry , pdf / thesis / review
Ali
what are the products of Nano chemistry?
Maira Reply
There are lots of products of nano chemistry... Like nano coatings.....carbon fiber.. And lots of others..
learn
Even nanotechnology is pretty much all about chemistry... Its the chemistry on quantum or atomic level
learn
Google
da
no nanotechnology is also a part of physics and maths it requires angle formulas and some pressure regarding concepts
Bhagvanji
hey
Giriraj
Preparation and Applications of Nanomaterial for Drug Delivery
Hafiz Reply
revolt
da
Application of nanotechnology in medicine
has a lot of application modern world
Kamaluddeen
yes
narayan
what is variations in raman spectra for nanomaterials
Jyoti Reply
ya I also want to know the raman spectra
Bhagvanji
I only see partial conversation and what's the question here!
Crow Reply
what about nanotechnology for water purification
RAW Reply
please someone correct me if I'm wrong but I think one can use nanoparticles, specially silver nanoparticles for water treatment.
Damian
yes that's correct
Professor
I think
Professor
Nasa has use it in the 60's, copper as water purification in the moon travel.
Alexandre
nanocopper obvius
Alexandre
what is the stm
Brian Reply
is there industrial application of fullrenes. What is the method to prepare fullrene on large scale.?
Rafiq
industrial application...? mmm I think on the medical side as drug carrier, but you should go deeper on your research, I may be wrong
Damian
How we are making nano material?
LITNING Reply
what is a peer
LITNING Reply
What is meant by 'nano scale'?
LITNING Reply
What is STMs full form?
LITNING
scanning tunneling microscope
Sahil
how nano science is used for hydrophobicity
Santosh
Do u think that Graphene and Fullrene fiber can be used to make Air Plane body structure the lightest and strongest. Rafiq
Rafiq
what is differents between GO and RGO?
Mahi
what is simplest way to understand the applications of nano robots used to detect the cancer affected cell of human body.? How this robot is carried to required site of body cell.? what will be the carrier material and how can be detected that correct delivery of drug is done Rafiq
Rafiq
if virus is killing to make ARTIFICIAL DNA OF GRAPHENE FOR KILLED THE VIRUS .THIS IS OUR ASSUMPTION
Anam
analytical skills graphene is prepared to kill any type viruses .
Anam
Any one who tell me about Preparation and application of Nanomaterial for drug Delivery
Hafiz
what is Nano technology ?
Bob Reply
write examples of Nano molecule?
Bob
The nanotechnology is as new science, to scale nanometric
brayan
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Damian
Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
Renato
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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Source:  OpenStax, High performance computing. OpenStax CNX. Aug 25, 2010 Download for free at http://cnx.org/content/col11136/1.5
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