[f2py] help with optional arguments

[pearu at cens.ioc.ee]

On Wed, 23 Nov 2005, Ryan Krauss wrote:

> I am new to f2py and I am having trouble figuring out how to make
> optional argument work as Cf2py statements.  I am working on a simple
> example and if I do this:
> C     Attempting to learn f2py
>       subroutine tf(s,TAU,mytf,k)
>       double precision k, TAU
>       complex s,mytf
> Cf2py intent(in) s,TAU
> Cf2py intent(optional) k = 5.0
> Cf2py intent(out) mytf
>       print*, "k=",k
>       mytf = k/(s*(TAU+s))
>       END
> 
> k is not optional when I import the module into python.

f2py does not understand the statement `intent(optional) k = 5.0` and so
it is ignored. Use

 Cf2py double precision k = 5.0

or

 Cf2py double precision optional :: k = 5.0

instead. Though it repeats the type declaration for k, it is currently the
only way to initialize `k` within Cf2py comment. Note that `optional` is
default whenever a variable has an initial value.

Pearu