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It has been said, “I don’t know what language they will be using to program high performance computers 10 years from now, but we do know it will be called FORTRAN.” At the risk of inciting outright warfare, we need to discuss the strengths and weaknesses of languages that are used for high performance computing. Most computer scientists (not computational scientists) train on a steady diet of C, C++, Just for the record, both the authors of this book are quite accomplished in C, C++, and FORTRAN, so they have no preconceived notions. or some other language focused on data structures or objects. When students encounter high performance computing for the first time, there is an immediate desire to keep programming in their favorite language. However, to get the peak performance across a wide range of architectures, FORTRAN is the only practical language.

When students ask why this is, usually the first answer is, “Because it has always been that way.” In one way this is correct. Physicists, mechanical engineers, chemists, structural engineers, and meteorologists do most programming on high performance computers. FORTRAN is the language of those fields. (When was the last time a computer science student wrote a properly working program that computed for a week?) So naturally the high performance computer vendors put more effort into making FORTRAN work well on their architecture.

This is not the only reason that FORTRAN is a better language, however. There are some fundamental elements that make C, C++, or any data structures-oriented language unsuitable for high performance programming. In a word, that problem is pointers . Pointers (or addresses) are the way good computer scientists construct linked lists, binary trees, binomial queues, and all those nifty data structures. The problem with pointers is that the effect of a pointer operation is known only at execution time when the value of the pointer is loaded from memory. Once an optimizing compiler sees a pointer, all bets are off. It cannot make any assumptions about the effect of a pointer operation at compile time. It must generate conservative (less optimized) code that simply does exactly the same operation in machine code that the high-level language described.

While the lack of pointers in FORTRAN is a boon to optimization, it seriously limits the programmer’s ability to create data structures. In some applications, especially highly scalable network-based applications, the use of good data structures can significantly improve the overall performance of the application. To solve this, in the FORTRAN 90 specification, pointers have been added to FORTRAN. In some ways, this was an attempt by the FORTRAN community to keep programmers from beginning to use C in their applications for the data structure areas of their applications. If programmers begin to use pointers throughout their codes, their FORTRAN programs will suffer from the same problems that inhibit optimization in C programs. In a sense FORTRAN has given up its primary advantage over C by trying to be more like C. The debate over pointers is one reason that the adoption rate of FORTRAN 90 somewhat slowed. Many programmers prefer to do their data structure, communications, and other bookkeeping work in C, while doing the computations in FORTRAN 77.

FORTRAN 90 also has strengths and weaknesses when compared to FORTRAN 77 on high performance computing platforms. FORTRAN 90 has a strong advantage over FORTRAN 77 in the area of improved semantics that enable more opportunities for advanced optimizations. This advantage is especially true on distributed memory systems on which data decomposition is a significant factor. (See [link] .) However, until FORTRAN 90 becomes popular, vendors won’t be motivated to squeeze the last bit of performance out of FORTRAN 90.

So while FORTRAN 77 continues to be the mainstream language for high performance computing for the near future, other languages, like C and FORTRAN 90, have their limited and potentially increasing roles to play. In some ways the strongest potential challenger to FORTRAN in the long run may come in the form of a numerical tool set such as Matlab. However, packages such as Matlab have their own set of optimization challenges that must be overcome before they topple FORTRAN 77’s domination.

Questions & Answers

Application of nanotechnology in medicine
what is variations in raman spectra for nanomaterials
Jyoti Reply
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
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
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
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
Stoney Reply
why we need to study biomolecules, molecular biology in nanotechnology?
Adin Reply
?
Kyle
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
Adin
why?
Adin
what school?
Kyle
biomolecules are e building blocks of every organics and inorganic materials.
Joe
anyone know any internet site where one can find nanotechnology papers?
Damian Reply
research.net
kanaga
sciencedirect big data base
Ernesto
Introduction about quantum dots in nanotechnology
Praveena Reply
hi
Loga
what does nano mean?
Anassong Reply
nano basically means 10^(-9). nanometer is a unit to measure length.
Bharti
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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