If a procedure has a dummy argument that is an allocatable, then an explicit interface is required in any calling scope. (There are numerous things that require an explicit interface, an allocatable dummy is but one.) You can provide that explicit interface yourself by putting an interface block for your subroutine inside the main program. … 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
You’re looking for g++ main.o print_hi.o -o main -lgfortran to link in the standard Fortran libraries. You can also use gfortran by passing -lstdc++.
You can do that using reshape and shape intrinsics. Something like: INTEGER, DIMENSION(3, 3) :: array array = reshape((/ 1, 2, 3, 4, 5, 6, 7, 8, 9 /), shape(array)) But remember the column-major order. The array will be 1 4 7 2 5 8 3 6 9 after reshaping. So to get: 1 2 … Read more
A good starting point is the great book The Science of Programming Matrix Computations by Robert A. van de Geijn and Enrique S. Quintana-OrtÃ. They provide a free download version. BLAS is divided into three levels: Level 1 defines a set of linear algebra functions that operate on vectors only. These functions benefit from vectorization … Read more
On macOS Big Sur v11.1: Relevant SO post: https://apple.stackexchange.com/questions/408999/gfortran-compiler-error-on-mac-os-big-sur The fix is to add the stdlib to your $LIBRARY_PATH. For some reason or another it isn’t in your standard $PATH anymore on 11.1. export LIBRARY_PATH=”$LIBRARY_PATH:/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/lib” (or add it to login file and restart terminal).
Type these two lines in your terminal, direct quote: curl -O http://r.research.att.com/libs/gfortran-4.8.2-darwin13.tar.bz2 sudo tar fvxj gfortran-4.8.2-darwin13.tar.bz2 -C / It will download you the gfortran for Mavericks (which is missing in your system at the moment) and will install it in your system. At least, this solved the same problem for me (I’m running late 2011 … Read more
Assumed shape dummy arguments (those with (:)) require explicit interface to the procedure to be available at the call site. That means the calling code must know how exactly the subroutine header looks like. See also Module calling an external procedure with implicit interface That explicit interface can be provided in several ways 1. preferred … Read more
The best practice is to place your procedures (subroutines and functions) in a module and then “use” that module from your main program or other procedures. You don’t need to “use” the module from other procedures of the same module. This will make the interface of the procedure explicit so that the calling program or … Read more