First, some terminology. Consider the dummy arguments declared as real :: a(n) ! An explicit shape array real :: b(:) ! An assumed shape array real, allocatable :: c(:) ! A deferred shape array (allocatable) real, pointer :: d(:) ! A deferred shape array (pointer) real :: e(*) ! An assumed size array real :: … Read more
The “normal” interfaces — known by the standard as specific interface blocks (as you use in the title of the question) — are just normal interface blocks for some procedure. Therefore: interface subroutine foo_sub end subroutine end interface means that there exists an actual (external) subroutine named foo_sub and it conforms to the specified interface. … Read more
For the sake of clarity, I’ll briefly mention terminology. The two arrays are both local variables and arrays of rank 1. alloc_array is an allocatable array; automatic_array is an explicit-shape automatic object. Being local variables their scope is that of the procedure. Automatic arrays and unsaved allocatable arrays come to an end when execution of … Read more
To add to Vladimir F’s answer I’ll mention that gfortran 5.0 (but not earlier) supports the IEEE intrinsic modules. Instead of real x x=0 x=0/x one can use use, intrinsic :: iso_fortran_env use, intrinsic :: ieee_arithmetic integer(int32) i real(real32) x x = ieee_value(x, ieee_quiet_nan) i = transfer(x,i) This gives you a little flexibility over which … Read more
You need to factor the matrix (by calling dgetrf) before you can solve the system using dgetrs. Alternatively, you can use the dgesv routine, which does both steps for you. By the way, you don’t need to declare the interfaces yourself, they are in the Accelerate headers: // LAPACK test code #include <iostream> #include <vector> … Read more
You can tell gfortran where your module files (.mod files) are located with the -I compiler flag. In addition, you can tell the compiler where to put compiled modules with the -J compiler flag. See the section “Options for directory search” in the gfortran man page. I use these to place both my object (.o … Read more
The easiest way is like this (reverse the order of indexes for row and column if necessary and add declarations for all variables I skipped to keep it short). It first reads the file and determines the number of lines. Then it rewinds the file to start from the beginning and reads the known number … Read more
The number 865398.78 is represented in single precision in your code. Single precision can handle about 7 significant digits, while your number has 8. You can make it double precision by writing x=x+865398.78_8
When you have polymorphism like this there are two things to consider about an object: its dynamic type and its declared type. The parameters component of test_mask (base_mask) is declared as class(base_pars),pointer :: parameters Such a component therefore has declared type base_pars. Come the pointer assignment mask_test%parameters=>par_test mask_test%parameters has dynamic type the same as par_test: … Read more
You are correct that m31tensorprod being an internal function means that you do not have to declare it in the main program. In the jargon: it has an explicit interface. However, that is not the problem with your code. What is going wrong is with the function definition itself. [Admittedly the compiler message isn’t too … Read more