Yes. The OpenMP 4 target constructs were designed to support a wide range of accelerators. Compiler support for NVIDIA GPUs is available from GCC 7+ (see 1 and 2, although the latter has not been updated to reflect OpenMP 4 GPU support), Clang (see 3,4,5), and Cray. Compiler support for Intel GPUs is available in … Read more
Rename your file from First.f to First.f90. You have encountered an issue which is easily avoided. Compilers generally assume that .f files are written in what is known as fixed source form, which has been obsolescent since Fortran 90. With the .f90 suffix your compiler should expect to encounter free source form and not complain … Read more
If you have a Fortran 2003 compiler, the intrinsic module iso_fortran_env defines the variables input_unit, output_unit and error_unit which point to standard in, standard out and standard error respectively. I tend to use something like #ifdef f2003 use, intrinsic :: iso_fortran_env, only : stdin=>input_unit, & stdout=>output_unit, & stderr=>error_unit #else #define stdin 5 #define stdout 6 … Read more
Yes, Fortran has procedure pointers, so you can in effect alias a function name. Here is a code example which assigns to the function pointer “f_ptr” one function or the other. Thereafter the program can use “f_ptr” and the selected function will be invoked. module ExampleFuncs implicit none contains function f1 (x) real :: f1 … Read more
Bare minimum -Og/-O0 -O0 basically tells the compiler to make no optimisations. Optimiser can remove some local variables, merge some code blocks, etc. and as an outcome it can make debugging unpredictable. The price for -O0 option is very slow code execution, but starting from version 4.8 GCC compilers (including the Fortran one) accept a … Read more
The form real, dimension(:) :: arr declares an assumed-shape array, while the form real :: arr(*) declares an assumed-size array. And, yes, there are differences between their use. The differences arise because, approximately, the compiler ‘knows’ the shape of the assumed-shape array but not of the assumed-size array. The extra information available to the compiler … Read more
Your problem is that you need to install a Fortran compiler to build scipy. Also, if you already have a numpy that’s built with Fortran support disabled, you may have to replace it. Some of Apple’s pre-installed Python versions have such a numpy build pre-installed. The easiest way to get Fortran is with Homebrew. As … Read more
Compiling to object files first is called separate compilation. There are many advantages and a few drawbacks. Advantages: easy to transform object files (.o) to libraries and link to them later many people can work on different source files at the same time faster compiling (you don’t compile the same files again and again when … Read more
I took a look at some of the stuff in the latest Fortran standards, and frankly I’m impressed. A lot of what I hated about the language 20 years ago is gone now. No more line numbers and special columns (may they burn in hell). Fortran has been heavily used in engineering circles for 50 … Read more
These two intrinsics report different types of time. system_clock reports “wall time” or elapsed time. cpu_time reports time used by the CPU. On a multi-tasking machine these could be very different, e.g., if your process shared the CPU equally with three other processes and therefore received 25% of the CPU and used 10 cpu seconds, … Read more