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<P>Dear Sir or Mada,</P>
<P> </P>
<P>Thank you very much for your kind suggestion. <IMG height=12 src="http://graphics.hotmail.com/emthup.gif" width=12><BR></P></DIV>
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<DIV></DIV>>Well, for my little experience, optimizing FORTRAN is a different
<DIV></DIV>>matter than optimizing C code (incidentally generated by a >FORTRAN-to-C translator): the former should be easier to >optimize (or, at least, producing optimized code from >FORTRAN should be a better understood problem than producing >optimized >code from C).
<DIV></DIV>>
<DIV></DIV>>But be sure to have a look at the optimizing options available for gcc
<DIV></DIV>>(i.e. even with -O3 it doesn't always unroll loops unless you tell it
<DIV></DIV>>explicitly).
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<P>Actually, I already used the -O3 during compiling.</P>
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<P>The g77 was used in compiling the fortran source code,</P>
<P>and f2c and gcc were also used, and the computational</P>
<P>speed is comparable (but much slow than other compilers,</P>
<P>say, absoft fortran)</P>
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<P>>I'd say that you have basically four choices: </P>
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<DIV></DIV>>1) Stick to FORTRAN, and buy a proprietary compiler targeted to the
<DIV></DIV>> platform of you choice.
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<DIV></DIV>> This already gave you very good results, from what you said.
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<P> </P>
<P>Those commercial compilers are too expensive.</P>
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<DIV></DIV>>2) Port the FORTRAN code to C by hand, without using an automatic
<DIV></DIV>> translator (which probably doesn't generate very good C), and buy a
<DIV></DIV>> proprietary C compiler targeted to the platform of your choice.
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<DIV></DIV>> This should give equally good results as (1), but with more effort,
<DIV></DIV>> and you end buying a proprietary compiler anyways.
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<P> </P>
<P>Not only the "g77 (or f77)" (and "f2c + gcc") are slow but also</P>
<P>the gcc is slow.</P>
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<P>>3) Port the FORTRAN code to C and use gcc, optimizing the code by >hand where needed using inline assembly. </P>
<P>> This is the solution used for the Linux kernel: it works, but </P>
<DIV></DIV>> requires a lot of effort and knowledge.
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<P> </P>
<P>Good idea.</P>
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<DIV></DIV>>3bis) Port the FORTRAN code to C, and use GNU GMP
<DIV></DIV>> (http://swox.com/gmp/#DOC) to do math. GMP functions are already
<DIV></DIV>> optimized by hand for several platforms, using inline
<DIV></DIV>> assembly. YMMV.
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<P>Yes. But it seems not easy to use the GMP, right?</P>
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<P>>4) Stay with f2c + gcc. It works, slowly, but it works. </P>
<DIV><IMG height=12 src="http://graphics.hotmail.com/emcrook.gif" width=12></DIV>
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<DIV>Thank you very much again.</DIV>
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<DIV>Ray</DIV></div><br clear=all><hr>Get your FREE download of MSN Explorer at <a href='http://g.msn.com/1HM301601/10'>http://explorer.msn.com</a>.<br></html>
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