Ifort and gfortran do not use the same block size for record length by default. In ifort, the value of recl in your open statement is in 4-byte blocks, so your record length isn’t 985,600 bytes, it is 3,942,400 bytes long. That means the records are written at intervals of 3.9 million bytes. gfortran uses … Read more
Fortran doesn’t automatically skip comments lines in input files. You can do this easily enough by first reading the line into a string, checking the first character for your comment symbol or search the string for that symbol, then if the line is not a comment, doing an “internal read” of the string to obtain … Read more
You have some lengths 12 in the constructor, so it may be better to use length 12. Also, use instead character(len=12), dimension(5) :: models = [character(len=12) :: “feddes.swp”, & “jarvis89.swp”, “jarvis10.swp”, “pem.swp”, “van.swp”] Possibly even better, if you have compiler support, is character(len=*), dimension(*) :: …
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 random number generator produces pseudo-random numbers. To get different numbers each run, you need to initialise the random seed at the start of your program. This picks a different starting position in the pseudo-random stream.
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
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
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
I had the same problem when trying to install the CRAN package VGAM on Ubuntu 12.10 64bit. I already had r-base-dev installed, but Andrew Redd’s second comment to Dirk Eddelbuettel’s answer worked for me. Specifically, I was getting two errors: /usr/bin/ld: cannot find -lgfortran /usr/bin/ld: cannot find -lquadmath Which were fixed by the lines: sudo … Read more