<< Chapter < Page Chapter >> Page >

A = A + B

in lieu of:

DO J=1,M DO I=1,NA(I,J) = A(I,J) + B(I,J) END DOEND DO

Naturally, when you want to combine two arrays in an operation, their shapes have to be compatible. Adding a seven-element vector to an eight-element vector doesn't make sense. Neither would multiplying a 2×4 array by a 3×4 array. When the two arrays have compatible shapes, relative to the operation being performed upon them, we say they are in shape conformance , as in the following code:

DOUBLE PRECISION A(8), B(8) ...A = A + B

Scalars are always considered to be in shape conformance with arrays (and other scalars). In a binary operation with an array, a scalar is treated as an array of the same size with a single element duplicated throughout.

Still, we are limited. When you reference a particular array, A, for example, you reference the whole thing, from the first element to the last. You can imagine cases where you might be interested in specifying a subset of an array. This could be either a group of consecutive elements or something like "every eighth element" (i.e., a non-unit stride through the array). Parts of arrays, possibly noncontiguous, are called array sections .

FORTRAN 90 array sections can be specified by replacing traditional subscripts with triplets of the form a:b:c , meaning "elements a through b , taken with an increment of c ." You can omit parts of the triplet, provided the meaning remains clear. For example, a:b means "elements a through b ;" a: means "elements from a to the upper bound with an increment of 1." Remember that a triplet replaces a single subscript, so an n -dimension array can have n triplets.

You can use triplets in expressions, again making sure that the parts of the expression are in conformance. Consider these statements:

REAL X(10,10), Y(100) ...X(10,1:10) = Y(91:100) X(10,:) = Y(91:100)

The first statement above assigns the last 10 elements of Y to the 10th row of X . The second statement expresses the same thing slightly differently. The lone " : " tells the compiler that the whole range (1 through 10) is implied.

Fortran 90 intrinsics

FORTRAN 90 extends the functionality of FORTRAN 77 intrinsics, and adds many new ones as well, including some intrinsic subroutines. Most can be array-valued : they can return arrays sections or scalars, depending on how they are invoked. For example, here's a new, array-valued use of the SIN intrinsic:

REAL A(100,10,2) ...A = SIN(A)

Each element of array A is replaced with its sine. FORTRAN 90 intrinsics work with array sections too, as long as the variable receiving the result is in shape conformance with the one passed:

REAL A(100,10,2) REAL B(10,10,100)... B(:,:,1) = COS(A(1:100:10,:,1))

Other intrinsics, such as SQRT , LOG , etc., have been extended as well. Among the new intrinsics are:

  • FORTRAN 90 has vector reductions such as MAXVAL , MINVAL , and SUM . For higher-order arrays (anything more than a vector) these functions can perform a reduction along a particular dimension. Additionally, there is a DOT_PRODUCT function for the vectors.
  • Intrinsics MATMUL and TRANSPOSE can manipulate whole matrices.
  • RESHAPE allows you to create a new array from elements of an old one with a different shape. SPREAD replicates an array along a new dimension. MERGE copies portions of one array into another under control of a mask. CSHIFT allows an array to be shifted in one or more dimensions.
  • SHAPE , SIZE , LBOUND , and UBOUND let you ask questions about how an array is constructed.
  • Two other new reduction intrinsics, ANY and ALL , are for testing many array elements in parallel.

Questions & Answers

Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
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
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
what school?
biomolecules are e building blocks of every organics and inorganic materials.
anyone know any internet site where one can find nanotechnology papers?
Damian Reply
sciencedirect big data base
Introduction about quantum dots in nanotechnology
Praveena Reply
what does nano mean?
Anassong Reply
nano basically means 10^(-9). nanometer is a unit to measure length.
do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
Damian Reply
absolutely yes
how to know photocatalytic properties of tio2 nanoparticles...what to do now
Akash Reply
it is a goid question and i want to know the answer as well
characteristics of micro business
for teaching engĺish at school how nano technology help us
Do somebody tell me a best nano engineering book for beginners?
s. Reply
there is no specific books for beginners but there is book called principle of nanotechnology
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
what is the actual application of fullerenes nowadays?
That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.
what is the Synthesis, properties,and applications of carbon nano chemistry
Abhijith Reply
Mostly, they use nano carbon for electronics and for materials to be strengthened.
is Bucky paper clear?
carbon nanotubes has various application in fuel cells membrane, current research on cancer drug,and in electronics MEMS and NEMS etc
so some one know about replacing silicon atom with phosphorous in semiconductors device?
s. Reply
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
Do you know which machine is used to that process?
how to fabricate graphene ink ?
for screen printed electrodes ?
What is lattice structure?
s. Reply
of graphene you mean?
or in general
in general
Graphene has a hexagonal structure
On having this app for quite a bit time, Haven't realised there's a chat room in it.
what is biological synthesis of nanoparticles
Sanket Reply
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
Privacy Information Security Software Version 1.1a
Got questions? Join the online conversation and get instant answers!
Jobilize.com Reply

Get the best Algebra and trigonometry course in your pocket!

Source:  OpenStax, High performance computing. OpenStax CNX. Aug 25, 2010 Download for free at http://cnx.org/content/col11136/1.5
Google Play and the Google Play logo are trademarks of Google Inc.

Notification Switch

Would you like to follow the 'High performance computing' conversation and receive update notifications?

Lakeima Roberts
Start Quiz