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Increasing double loop efficiency
I have the following double loop; DO i=1,100 DO j=1,100 S(i,j)= S(i,j)+ALPHA*exp[(real(i)/b1)**2]*exp[(real(j)/b2)**2] ENDDO ENDDO Here, S is a 100x100 symmetric REAL array, ALPHA, b1, and b2 are REAL constants. I am hoping to incorporate LAPACK dgemm or some other library function... -
Preventing the addition of C-style comments in gfortran compilation
Hi, I am compiling a code (VASP) using gfortran/openmpi. The codes includes about 50 files. When I issue "make", the compilation crashes because somehow the following lines get added to .f files. /* Copyright (C) 1991-2016 Free Software Foundation, Inc. This file is part of the GNU C... -
Printing in a fortran MPI/OpenMP environment
This is likely a very simple question. I am running a fortran code compiled in hybrid openmp/openmpi. The code runs on 2 nodes (128 processors) with 32 MPI processes and 4 threads/MPI process. I am attempting to verify that a variable involved in the calculations on all the MPI processes and... -
Broadcasting a REAL number to another file
Hi, I am modifying a large code called Perturbo. Here I attempt to describe what the problem is with a simple example. I understand that this information may not be enough. The code has a module file called polar_dispersion.f90. I would like to broadcast the value of a REAL called conc (not... -
Do loop in ascending and descending order
Hello, I have the following code which generates a 3-d grid between 0 and nmax (usually the three nmax's are around 100): program Mesh implicit none integer, parameter :: npts=64 integer::ntot,n,n1,n2,n3,nmax(3), nstart(3),tmp(3),k(3,npts) nmax(1)=4... -
Reading files inside many numbered folders
Hello, I have a number of folders labeled K00001 to K00100 in my scratch folder. Each folder contains a file called a.dat. From my scratch folder, I would like to go into each folder, read the content of a.dat, save the necessary information to an array and then move on to the next folder. I... -
NaN output outside but not inside DO loop
Dear Fortran Users, In the following code, I can print all the values for conc_h inside the first DO loop over i before ENDDO and the total conc_h right after the ENDDO. When I try to print conc_e inside the second DO loop over i, I get REAL values but when I put the print statement right after... -
Transfer of data from inside a subroutine to main program
Hello, The following program does not compile but returns the following error: error #6236: A specification statement cannot appear in the executable section. All I would like to do is to be able to transfer the array r(i) from the subroutine to the main program without using the "contents"... -
Segmentation fault with write statement
Hello, I am using a fortran code called EPW and would like to extract a matrix A(ibnd,imode,ik) from the code. This is how I have tried to extract the matrix: Open file to write to Allocate(A(nbnd,nmodes,nkf)) Loop iq ! from 1 to nqf Loop ik ! from 1 to nkf Loop ibnd ! from 1 to nbnd...
