Fortran Fortran functions as arguments of functions

[Biederman]

Hi all,

It is my first time to resort to the help of members of this forum :)

My question is related to programming in fortran but I am rather new with it.

So here is the question:Can I use user defined functions as arguments of a user defined functions in Fortran?

I have written a simple code for numerical integration but when I run the program I get an error message "segmentation fault (core dumped)"

Here is the code:
C%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

PROGRAM NUMERIC

REAL :: INTEG,SINE

PRINT*,INTEG(SINE,0.0,3.14159,100)

END

FUNCTION INTEG(FUNC,A,B,N)

INTERFACE
FUNCTION FUNC(X)
REAL :: FUNC, X
END FUNCTION
END INTERFACE
REAL :: A,B,INTEG,H,TOTAL,FUNC
INTEGER N,I


! THE INTEGRATION FORMULA IS: INTEG=H*(0.5*FUNC(X0)+FUNC(X1)+...+0.5*FUNC(XN))

H=(B-A)/N

TOTAL=0.5*(FUNC(A)+FUNC(B))
DO I=1,N-1
TOTAL=TOTAL+FUNC(A+I*H)
ENDDO
INTEG=TOTAL*H
RETURN
END FUNCTION INTEG



FUNCTION SINE(X)

REAL :: X,SINE

SINE=X*SIN(X)

RETURN
END
C%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
After running I get: Segmentation fault (core dumped)

I don't know what's wrong with the code, since there is no error message during the compilation.

I would appreciate your help.

 

[SteamKing]

You should research the EXTERNAL declaration statement if you are passing function or subroutine names as arguments.

 

[Biederman]

Thank you SteamKing. I've got the program working after checking the EXTERNAL statement, as you had suggested.

Thanks again