See also What are extern variables in C. This is mentioned in the C standard in informative Annex J as a common extension: J.5.11 Multiple external definitions There may be more than one external definition for the identifier of an object, with or without the explicit use of the keyword extern; if the definitions disagree, … Read more
The most probable cause for this behaviour is that your stack size limit is too small (for whatever reason). Since e_in is private to each OpenMP thread, one copy per thread is allocated on the thread stack (even if you have specified -heap-arrays!). 202000 elements of REAL(KIND=8) take 1616 kB (or 1579 KiB). The stack … Read more
you can write to a unit, but you can also write to a string program foo character(len=1024) :: filename write (filename, “(A5,I2)”) “hello”, 10 print *, trim(filename) end program Please note (this is the second trick I was talking about) that you can also build a format string programmatically. program foo character(len=1024) :: filename character(len=1024) … Read more
In Fortran >=90, the best approach is use intrinsic functions to specify the precision you need — this guarantees both portability and that you get the precision that you need. For example, to obtain integers i and my_int that will support at least 8 decimal digits, you could use: integer, parameter :: RegInt_K = selected_int_kind … Read more
The KIND of a variable is an integer label which tells the compiler which of its supported kinds it should use. Beware that although it is common for the KIND parameter to be the same as the number of bytes stored in a variable of that KIND, it is not required by the Fortran standard. … Read more
It seems to me you are completely misunderstanding tho processes of compilation and running. These lines are suspicious: gfortran numcbas.f < numcbas_c.data g77 numcbas.f < numcbas_c.data There is no reason to redirect a data file to the compiler command. The compiler first has to create an executable program which you then can run with your … Read more