Print to standard output from a function defined in an Fortran module

by

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 – see 9.11p2 and p3 of F2003 or 9.12p2 of F2008.

A solution is to separate the function invocation from the io statement in the main program, i.e.

REAL :: a_temporary
...
a_temporary = plgndr(1,2,0.1)
PRINT *, a_temporary

Other alternatives in F2008 (but not F2003 – hence the [ ] parts in the first paragraph) include directing the output from the function to a different logical unit (note that WRITE (*, ... and PRINT ... reference the same unit).

In F2008 you could also replace the WRITE statement with a STOP statement with a message (the message must be a constant – which wouldn’t let you report the problematic values).

The potential for inadvertently invoking recursive IO is part of the reason that some programming styles discourage conducting IO in functions.

More Related Contents:

  1. Fortran 90 kind parameter
  2. Fortran: integer*4 vs integer(4) vs integer(kind=4)
  3. Unexpected “padding” in a Fortran unformatted file
  4. Is There a Better Double-Precision Assignment in Fortran 90?
  5. Fortran assignment on declaration and SAVE attribute gotcha
  6. MPI_Recv overwrites parts of memory it should not access
  7. changing array dimensions in fortran
  8. Why should I use interfaces?
  9. Fortran OpenMP program shows no speedup of CPU_TIME()
  10. Where to put `implicit none` in Fortran
  11. Function has no implicit type
  12. ‘*’ and ‘/’ not recognized on input by a read statement
  13. Reading data file in Fortran with known number of lines but unknown number of entries in each line
  14. What are the ways to pass a set of variable values through the subroutine to a function without common block?
  15. how to write wrapper for ‘allocate’
  16. gfortran does not allow character arrays with varying component lengths
  17. How do I do big integers in Fortran?
  18. What is the purpose of result variables in Fortran?
  19. Line truncated, Syntax error in argument list
  20. Using a deferred-length character string to read user input
  21. Function in fortran, passing array in, receiving array out
  22. Reading writing fortran direct access unformatted files with different compilers
  23. Strange label usage for an IF condition in a DO loop [duplicate]
  24. Fortran OpenMP with subroutines and functions
  25. Error: Nonnegative width required in format string at (1)
  26. Fortran array cannot be returned in function: not a DUMMY variable
  27. Using do loop in a Fortran 90 program to read different number of lines for n frames?
  28. Allocatable array valued function. gfortran vs ifort
  29. How to pass subroutine names as arguments in Fortran?
  30. Confusing double precision real in Fortran

Leave a Comment