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In this example, K has been declared as a COMMON variable. It is used only as a do-loop counter, so there really is no reason for it to be anything but local. However, because it is in a COMMON block, the call to AUX forces the compiler to store and reload K each iteration. This is because the side effects of the call are unknown.

So far, it looks as if we are preparing a case for huge main programs without any subroutines or functions! Not at all. Modularity is important for keeping source code compact and understandable. And frankly, the need for maintainability and modularity is always more important than the need for small performance improvements. However, there are a few approaches for streamlining subroutine calls that don’t require you to scrap modular coding techniques: macros and procedure inlining.

Remember, if the function or subroutine does a reasonable amount of work, procedure call overhead isn’t going to matter very much. However, if one small routine appears as a leaf node in one of the busiest sections of the call graph, you might want to think about inserting it in appropriate places in the program.


Macros are little procedures that are substituted inline at compile time. Unlike subroutines or functions, which are included once during the link, macros are replicated every place they are used. When the compiler makes its first pass through your program, it looks for patterns that match previous macro definitions and expands them inline. In fact, in later stages, the compiler sees an expanded macro as source code.

Macros are part of both C and FORTRAN (although the FORTRAN notion of a macro, the statement function , is reviled by the FORTRAN community, and won’t survive much longer). The statement function has been eliminated in FORTRAN 90. For C programs, macros are created with a #define construct, as demonstrated here:

#define average(x,y) ((x+y)/2) main (){ float q = 100, p = 50;float a; a = average(p,q);printf ("%f\n",a); }

The first compilation step for a C program is a pass through the C preprocessor, cpp . This happens automatically when you invoke the compiler. cpp expands #define statements inline, replacing the pattern matched by the macro definition. In the program above, the statement:

a = average(p,q);

gets replaced with:

a = ((p+q)/2);

You have to be careful how you define the macro because it literally replaces the pattern located by cpp . For instance, if the macro definition said:

#define multiply(a,b) (a*b)

and you invoked it as:

c = multiply(x+t,y+v);

the resulting expansion would be x+t*y+v — probably not what you intended.

If you are a C programmer you may be using macros without being conscious of it. Many C header files ( .h ) contain macro definitions. In fact, some “standard” C library functions are really defined as macros in the header files. For instance, the function getchar can be linked in when you build your program. If you have a statement:


Questions & Answers

find the 15th term of the geometric sequince whose first is 18 and last term of 387
Jerwin Reply
I know this work
The given of f(x=x-2. then what is the value of this f(3) 5f(x+1)
virgelyn Reply
hmm well what is the answer
how do they get the third part x = (32)5/4
kinnecy Reply
can someone help me with some logarithmic and exponential equations.
Jeffrey Reply
sure. what is your question?
okay, so you have 6 raised to the power of 2. what is that part of your answer
I don't understand what the A with approx sign and the boxed x mean
it think it's written 20/(X-6)^2 so it's 20 divided by X-6 squared
I'm not sure why it wrote it the other way
I got X =-6
ok. so take the square root of both sides, now you have plus or minus the square root of 20= x-6
oops. ignore that.
so you not have an equal sign anywhere in the original equation?
is it a question of log
I rally confuse this number And equations too I need exactly help
But this is not salma it's Faiza live in lousvile Ky I garbage this so I am going collage with JCTC that the of the collage thank you my friends
Commplementary angles
Idrissa Reply
im all ears I need to learn
right! what he said ⤴⤴⤴
what is a good calculator for all algebra; would a Casio fx 260 work with all algebra equations? please name the cheapest, thanks.
Kevin Reply
a perfect square v²+2v+_
Dearan Reply
kkk nice
Abdirahman Reply
algebra 2 Inequalities:If equation 2 = 0 it is an open set?
Kim Reply
or infinite solutions?
The answer is neither. The function, 2 = 0 cannot exist. Hence, the function is undefined.
Embra Reply
if |A| not equal to 0 and order of A is n prove that adj (adj A = |A|
Nancy Reply
rolling four fair dice and getting an even number an all four dice
ramon Reply
Kristine 2*2*2=8
Bridget Reply
Differences Between Laspeyres and Paasche Indices
Emedobi Reply
No. 7x -4y is simplified from 4x + (3y + 3x) -7y
Mary Reply
how do you translate this in Algebraic Expressions
linda Reply
Need to simplify the expresin. 3/7 (x+y)-1/7 (x-1)=
Crystal Reply
. After 3 months on a diet, Lisa had lost 12% of her original weight. She lost 21 pounds. What was Lisa's original weight?
Chris Reply
what's the easiest and fastest way to the synthesize AgNP?
Damian Reply
types of nano material
abeetha Reply
I start with an easy one. carbon nanotubes woven into a long filament like a string
many many of nanotubes
what is the k.e before it land
what is the function of carbon nanotubes?
I'm interested in nanotube
what is nanomaterials​ and their applications of sensors.
Ramkumar Reply
what is nano technology
Sravani Reply
what is system testing?
preparation of nanomaterial
Victor Reply
Yes, Nanotechnology has a very fast field of applications and their is always something new to do with it...
Himanshu Reply
good afternoon madam
what is system testing
what is the application of nanotechnology?
In this morden time nanotechnology used in many field . 1-Electronics-manufacturad IC ,RAM,MRAM,solar panel etc 2-Helth and Medical-Nanomedicine,Drug Dilivery for cancer treatment etc 3- Atomobile -MEMS, Coating on car etc. and may other field for details you can check at Google
anybody can imagine what will be happen after 100 years from now in nano tech world
after 100 year this will be not nanotechnology maybe this technology name will be change . maybe aftet 100 year . we work on electron lable practically about its properties and behaviour by the different instruments
name doesn't matter , whatever it will be change... I'm taking about effect on circumstances of the microscopic world
how hard could it be to apply nanotechnology against viral infections such HIV or Ebola?
silver nanoparticles could handle the job?
not now but maybe in future only AgNP maybe any other nanomaterials
I'm interested in Nanotube
this technology will not going on for the long time , so I'm thinking about femtotechnology 10^-15
can nanotechnology change the direction of the face of the world
Prasenjit Reply
At high concentrations (>0.01 M), the relation between absorptivity coefficient and absorbance is no longer linear. This is due to the electrostatic interactions between the quantum dots in close proximity. If the concentration of the solution is high, another effect that is seen is the scattering of light from the large number of quantum dots. This assumption only works at low concentrations of the analyte. Presence of stray light.
Ali Reply
the Beer law works very well for dilute solutions but fails for very high concentrations. why?
bamidele 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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