FORTRAN input and output formatting rules are rather involved. Each input and ouptut statement has two arguments that have special meaning. For example READ (10,”(2I10)”) m,n The first argument is a file descriptor. Here it is 10. The second argument “(2I10)” is the format specifier. If you give an asterisk (*) as a format specifier … Read more
In the following, I’ll explain using the complete example below (which you can compile and link to try things): module mymodule contains integer function foo () foo = 1 end function integer function bar () integer :: foo bar = foo() end function end module program test use mymodule print *, bar() end In the … Read more
Your program does what is known as recursive IO – the initial call to plgndr is in the output item list of an IO statement (a print statement) [directing output to the console] – inside that function you then also attempt to execute another IO statement [that outputs to the console]. This is not permitted … Read more
Move the line end program to the end of your source file and, in its place, write the line contains As you have written your program it has no knowledge of the function test, which is what the compiler is telling you. I have suggested one of the ways in which you can provide the … Read more
The validity of code like integer, allocatable :: array(:) array = (/1,2,3/) end depends on the standard of Fortran used to interpret it. Fortran 2003 introduced the concept of automatic allocation on intrinsic assignment. Before Fortran 2003 the array on the left-hand side of such an assignment statement must be allocated, and of the same … Read more
If you want to get the arguments fed to your program on the command line, use the (since Fortran 2003) standard intrinsic subroutine GET_COMMAND_ARGUMENT. Something like this might work PROGRAM MAIN REAL(8) :: A,B integer :: num_args, ix character(len=12), dimension(:), allocatable :: args num_args = command_argument_count() allocate(args(num_args)) ! I’ve omitted checking the return status of … Read more
The implicit statement (including implicit none) applies to a scoping unit. Such a thing is defined as BLOCK construct, derived-type definition, interface body, program unit, or subprogram, excluding all nested scoping units in it This “excluding all nested scoping units in it” suggests that it may be necessary/desirable to have implicit none in each function … Read more
“explicit interface” means that the interface to the procedure (subroutine or function) is declared to the compiler. This allows the compiler to check consistency of arguments between calls to the procedure and the actual procedure. This can find a lot of programmer mistakes. You can do this writing out the interface with an interface statement … Read more
Yes, it has. It is just called differently. There are many things that you could do and will make your code not standard conforming, for which there is no requirement to for the processor (compiler) to diagnose such non-conformance (of course, many deviations must be diagnosed). Often the situations will be similar to C undefined-behaviour … 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