CODEWITHSUNDEEP
compiler-errorsfortran
mattiav27
mattiav27

Reputation: 685

Fortran Error: Type mismatch in argument ‘n’ at (1); passed REAL(4) to INTEGER(4)

I am learning Fortran, specifically modules. I wrote this simple code that should calculate the derivative of the sine function:

module constants
    real, parameter::x=3.14
    real, parameter::h=0.0001
end module constants

module derivata1

contains
    real function der1(n)
        use constants
        real::der
        der=(sin(x+h)-sin(x))/h
    end function der1
end module derivata1
program derivate
    use constants
    use derivata1
    implicit none
    real der1

    print *, der1(x)
end program derivate

I get the following error in gfortran.

der2.f90:40.10:

 real der1
          1
der2.f90:38.5:

 use derivata1
     2
Error: Symbol 'der1' at (1) conflicts with symbol from module 'derivata1', use-associated at (2)
der2.f90:44:15:

  print *, der1(x)
               1
Error: Type mismatch in argument ‘n’ at (1); passed REAL(4) to INTEGER(4)

I followed this and this posts, but with no result.

Where is my error?

Upvotes: 0

Views: 13872

Answers (1)

Vladimir F Героям слава
Vladimir F Героям слава

Reputation: 60008

You should use IMPLICIT NONE in all your compilation units.

Inside the module you have no IMPLICIT NONE so the argument n is implicitly integer because it is not declared to be otherwise.

Also, you should not do any

real der1

in the program where you want to use function der1 from a module, because that makes the function to be declared external. The compiler then thinks you are calling some other function der1 which is somewhere else, but not in that module.

Upvotes: 1

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