For the sake of future visitors, I suppose I’ll answer this even though it’s all answered in the comments above. As far as I’m aware, if your program is behaving properly, you cannot change the value of that parameter (“count”) in a call to MPI_Recv. Your argument status is too small, it should be an … Read more
I don’t think that there is some rationale behind such behavior. But as far as I know, Stefano, you used wrong terminology. In your code there is no assignment statement only variable (var) initialization using initialization expression (0). integer :: var = 0 ! type declaration & initialization integer :: var ! type declaration var … Read more
cpu_time() takes the time on the CPU, not the walltime. In parallel applications these are not the same. See here for details. Using system_clock() solves this problem: PROGRAM MAIN use omp_lib implicit none REAL*8 Times1,Times2 INTEGER I,J, iTimes1,iTimes2, rate real, allocatable, dimension(:) :: a allocate(a(1000)) CALL system_clock(count_rate=rate) DO J = 1, 1000 a(j)=j ENDDO ! … Read more
The following a literal Fortran translation of this answer. I had thought this was unnecessary, but the multiple differences in array indexing and memory layout might mean that it is worth doing a Fortran version. Let me start by saying that you generally don’t really want to do this – scatter and gather huge chunks … Read more
As Alexander Vogt says, interface blocks can be useful for providing generic identifiers and allowing certain compiler checks. If you’re using interface blocks to create generic identifiers you’re probably doing so within modules, so the main reason to write such blocks when modules aren’t about is for the explicit interfaces that they create in the … Read more
See the RESHAPE intrinsic, e.g. http://gcc.gnu.org/onlinedocs/gfortran/RESHAPE.html Alternatively, if you want to avoid the copy (in some cases an optimizing compiler might be able to do a reshape without copying, e.g. if the RHS array is not used afterwards, but I wouldn’t count on it), as of Fortran 2003 you can assign pointers to targets of … Read more
A real which isn’t marked as double precision will be assumed to be single precision. Just because sometime later you assign it to a double precision variable, or convert it to double precision, that doesn’t mean that the value will ‘magically’ be double precision. It doesn’t look ahead to see how the value will be … Read more
For unformated IO, Fortran compilers typically write the length of the record at the beginning and end of the record. Most but not all compilers use four bytes. This aids in reading records, e.g., length at the end assists with a backspace operation. You can suppress this with the new Stream IO mode of Fortran … Read more
A link-time error like these messages can be for many of the same reasons as for more general uses of the linker, rather than just having compiled a Fortran program. Some of these are covered in the linked question about C++ linking and in another answer here: failing to specify the library, or providing them … 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