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Are FORTRAN 77 programs faster than Fortran 90?

Today I read code from very popular number libraries written in FORTRAN 77, such as QUADPACK ( last updated in 1987 ), and I was wondering if there was any reason not to rewrite these libraries in Fortran 90 in addition to the large amount of work that it would put, given the big improvements Fortran 90 made to the language, including the free-form source, improved management structures, so GO TO can be forgotten, vectorized, interfaces, etc.

Is this because FORTRAN 77 compilers create more optimized code, perhaps better for parallel execution? Notice that I’m not even talking about Fortran 2003, which is only 8 years old: I’m talking about Fortran 90, so I assume it is fairly common and the compilers are ready. In any case, I have no contact with this industry.

Edit: janneb is right: LAPACK is actually written in Fortran 90.

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Well, as mentioned in "pst", "the large amount of work he will pose for" is a pretty significant reason.

Some additional minor points:

  • LAPACK IS Fortran 90, , , F77. , , , , .

  • F90, , , .

  • F90 ( g77!), , LAPACK, F90, , .

  • F77, , , F90. - , , , , . Fortran F77, F90, , .., (, , F90 , ).

  • , F90 +, , . DO.

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() -, . , , Fortran 90 , . , Fortran 90 Standard FORTRAN 77. FORTRAN 77. , Fortan 90 (, ), , , , . HPC.

. FORTAN 77 - . , Fortran 90 , , - , .

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, Fortran 77 :

(Fortran 90) , . . Fortran.

.

Fortran 90+ " ". gcc-fortran (gfortran) - N

a = a + 1

4 ,

do i = 1 , N
  a(i) = a(i) + 1
end do

, , gfortran - , .

"" ( , ) , - , Fortran Standard.

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F77 , F90, , , .

, . , , ( , , ... ).

Since these two (rather popular libraries) are still located in F77, it is obvious that the general opinion that the costs of rewriting them outweigh the benefits resulting from faster execution, as well as the benefits in terms of cost-effectiveness of the whole process.

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