| Re: How does IDL do ... [message #8880 is a reply to message #8871] |
Thu, 01 May 1997 00:00  |
peter
Messages: 80
Registered: February 1994
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Eric Williams (ewilliams@wesleyan.edu) wrote:
: I am also curious as to how IDL does matrix calculations. A simple example:
: If you want to operate on an 2D array with FORTRAN you need to write
: nested loops to work through the rows and columns and work with each
: element.
: In IDL you apply a function or WHERE statement to a whole array in one command.
: I am wondering if IDL is still doing the nested loops anyway, and
: therefore not really any faster at doing the job?
Indeed, IDL is doing the nested loops internally (how could it not,
unless you have more than one processor). Its speed on such operations
is comparable to the explicit loop code in C or FORTRAN. If you
do the explicit loop in IDL, it will be very slow.
So, you don't get to go faster than FORTRAN. On the other hand, you
don't often go much slower. And your program will be working a week
before that other guys!
: Finally, I am also trying to sell IDL to students as one good tool learn
: not only for astronomy but to open up future job possibilities in other
: fields. I have mentioned the following fields:
: bio medical imaging
: Are these correct? Can anyone pass on a few more?
Yes for biomedical imaging.
More generally, matrix processing / data visualization environments like
IDL (and Matlab, Mathematica, name your favorite) are heavily used by
folks doing algorithm development and writing of in-house processing
applications. Knowing about such tools and how to exploit them is a
Good Thing. You can try out methods of data processing much more
rapidly in such an environment.
Peter
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