Fortran Basics
in [Fortran]
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From: Tobias Burnus on 26 May 2010 11:33 On 05/26/2010 05:26 PM, baalzamon.moridin wrote: > [...]however, I do not have a fortran compiler. That can easily be solved: Simply install a free one, e.g., gfortran (http://gcc.gnu.org/wiki/GFortranBinaries) or g95 (http://www.g95.org/) Tobias
From: steve on 26 May 2010 11:44 On May 26, 8:26 am, "baalzamon.moridin" <baalzamon.mori...(a)gmail.com> wrote: > I've tried a few rather simple tutorials, however, I do not have a > fortran compiler. > Furthermore I really do not want to end up having to learn fortran > beyond what i need for translation. > Though I will act upon your advice and look up some more tutorials. If you do not have a Fortran compiler, how are you going to test that your Matlab translation gives the same result as the original Fortran code? gfortran and g95 are free compilers. http://gcc.gnu.org/wiki/GFortran http://www.g95.org/ There are a few commercially available compilers that provide a 'free' version under certain conditions (e.g., academic research or noncommercial use). Silverfrost is one such compiler. If the code is Fortran 77, you might take a peek at a book written by Clive Page. It can be found at http://www.star.le.ac.uk/~cgp/fortran.html search for "Professional Programmer's Guide to Fortran77" on the page. It a fairly concise book and with your background in Matlab, I suspect you could read it in a few hours. -- steve
From: dpb on 26 May 2010 12:48 baalzamon.moridin wrote: > Howdy there, > I am converting some fortran 77 code into matlab. There are various > questions that have cropped up. As I prgress through my conversion > process i will add them to this topic. For now my first question is; > What is 0.0D0? That is a DOUBLE PRECISION constant (as opposed to single, default floating point constant). W/O the "D", it is single precision. For a zero value, promotion to a double will still leave precisely zero; the difference occurs when the value is not exactly representable. Fortran will convert the single precision value to double on an assignment, but it is a single precision value in a double precision variable on doing so for a loose way of saying it. IOW, in general, the "D" is important for doubles. Here's a case where in Matlab it won't matter so much; Matlab uses double as it's default data type and so the effect of the "D" is gained implicitly w/o being specifically required. Given the questions you've asked in cs-sm and now this, you clearly need to start by finding a Fortran reference from the uni library or at a minimum link to the online manual of a compiler to be able to look up such stuff. --
From: baalzamon.moridin on 26 May 2010 12:58 With regards to testing, I have exe files of the original code. Thus I can test if my code yields the same results. I intend to write two versions, (i) Full conversion, (ii) Call the fortran code directly. Both will be tested for results. On a side note, one of my codes uses Assign a lot. Any ideas on what this does?
From: Richard Maine on 26 May 2010 13:17
baalzamon.moridin <baalzamon.moridin(a)gmail.com> wrote: > On a side note, one of my codes uses Assign a lot. Any ideas on > what this does? Oh, yukk! Assign is a bit of an abomination from the past, which is no longer in the language. Although simple enough in some ways, assign has an arcane collection of warts with surprising consequences. If used sparingly and in simple ways, it might not be too bad and can readily be translated into other constructs. But if a program uses it "a lot", I'd take that as a bad sign. Most programs I have seen that used it "a lot" were the kind of incomprehensible mess that was best handled by throwing them out and restarting from scratch. The short version is that assign assigns an integer variable with a value that is a statement label. You can then subsequently use that integer variable in a few limitted contexts as a stand-in for that statement label. -- Richard Maine | Good judgment comes from experience; email: last name at domain . net | experience comes from bad judgment. domain: summertriangle | -- Mark Twain |