Fortran 90/95 : passing parameters to functions

[pezze]

Hello, I have the following doubt, maybe someone can help me with this.
Suppose I have a general purpose routine that finds the zero of a function f(x), something like

subroutine fzero( func, x1, x2, xzero )
implicit none
real, intent(in) :: x1, x2 ! Upper and lower bounds where the zero lies
real, intent(out) :: xzero ! zero of the function here
interface
real function func(x)
implicit none
real, INTENT(in) :: x
end function func
end interface
...
f = func( x )
...
end subroutine fzero


My problem is the following. The function I want to find the zero depends on some parameter, say alpha, so it would be something like function(x,alpha)
Now, to use the previous general purpose routine I need to input the alpha in some other way. One possibility is to put "alpha" in a module, something like

module parameter
implicit none
real :: alpha
end module parameter

and then define the function

real func( x )
use parameter
...
end func

That would work. But do you know of any other way of doing the same thing?

Thanks for your help!

 

[Dr Transport]

Why not defing the function with the parameter alpha to begin with, then set it equal to some value like 1 when it doesn't matter.

 

[pezze]

Why not defing the function with the parameter alpha to begin with, then set it equal to some value like 1 when it doesn't matter.

The problem is that the general purpose subroutine fzero does not allow the function func(x) to have additional parameters.

 

[Dr Transport]

try passing y = ax into the function...

 

[pezze]

That doesn't quite work, I have many parameters, but thanks anyway!