Calling functions

[GerritGroot]

Hi,

Using gfortran, if I have a code like

[COLOR=purple]PROGRAM[/color] [COLOR=blue]Test[/color]
[COLOR=purple]IMPLICIT NONE[/color]
[COLOR=purple]REAL[/color] :: [COLOR=blue]y,MyFunc[/color]
y=[COLOR=blue]MyFunc[/color](2.)
[COLOR=purple]WRITE[/color](*,*)y
[COLOR=purple]END PROGRAM[/color] [COLOR=blue]Test[/color]

[COLOR=purple]REAL FUNCTION[/color] [COLOR=blue]MyFunc[/color](x)
[COLOR=purple]REAL, INTENT[/color](IN) :: x
MyFunc=x**2
[COLOR=purple]END FUNCTION[/color] [COLOR=blue]MyFun[/color]

that works and another one like

[COLOR=purple]PROGRAM[/color] [COLOR=blue]Test[/color]
[COLOR=purple]IMPLICIT NONE[/color]
[COLOR=purple]REAL[/color] :: [COLOR=blue]MyFunc[/color]
[COLOR=purple]WRITE[/color](*,*)[COLOR=blue]MyFunc[/color](2.)
[COLOR=purple]END PROGRAM[/color] [COLOR=blue]Test[/color]

[COLOR=purple]REAL FUNCTION[/color] [COLOR=blue]MyFunc[/color](x)
[COLOR=purple]REAL, INTENT[/color](IN) :: x
MyFunc=x**2
[COLOR=purple]END FUNCTION[/color] [COLOR=blue]MyFun[/color]

That doesn't work. What can be the cause?
(In the example they both work btw, but the second option in my code causes gfortran's executable to get stuck in a sort of endless loop)

Thanks,

Gerrit

(My reaction may be slow this week, lots of meetings and so on..)

 

[melmacianalf]

Seems like it has to do with recursive input/output. Not sure how well this is supported by gfortran. Your simple example works with gfortran. Can you post some example which can reproduce the "... in a sort of endless loop

 

[melmacianalf]

BTW, which version of gfortran creates the problem? Did u enable optimization?

 

[salgerman]

First of all, there is a typo at the end of the function....the function name's got a missing 'c'.

Second, What happens if you enclose your function call in a set of parenthesis, you know, the one after the WRITE statement? Does it make a difference?

I use g95 and the program works just fine...but I seem to recall some problem along time ago, either in fortran or something else and I thought I had something to do with evaluation on the spot, where I couldn't "write(*,*) myfun(3)+3" but I could "write(*,*) (myfun(3)+3)" and I figure the parenthesis were helping in including another evaluation layer BEFORE handing over the result to the write statement.

my 2 cents

 

[FJacq]

Your program is perfect if you don't use IO statement within the function.

It exits other limitations with non pure function, like modifying a global variable itself used in the write statement calling the function, but this is rather rare.

François Jacq