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From: Richard Maine on 29 Mar 2010 11:55
Enthalpy <epagone(a)email.it> wrote:

> I thought the PASS/NOPASS attribute was necessary just when the
> CONTAINS statement is present in a derived type definition (Chapman,
> "Fortran 95-2003 for scientists and engineers (3rd ed.)"); am I wrong?

I don't have a copy of that book to see what they say (I wasn't too fond
of earlier of his books), but that is wrong. The PASS attribute applies
to procedure type bindings (that's the stuff after CONTAINS in a
derived-type definition) and to procedure components.

--
Richard Maine | Good judgment comes from experience;
email: last name at domain . net | experience comes from bad judgment.
domain: summertriangle | -- Mark Twain
From: Enthalpy on 1 Apr 2010 12:46
Many thanks to James and Richard for their valuable answers, I changed
my code accordingly.

I also committed other corrections to my code, but I'm still not
through. Now my troubles are on the unknowns side.

I'm trying to use the following derived type

INTEGER, PARAMETER :: dp = SELECTED_REAL_KIND(15,100)
TYPE :: arr_ptr
REAL(dp), POINTER :: p => NULL()
END TYPE arr_ptr

in the form of allocatable array

TYPE(arr_ptr), DIMENSION(:), ALLOCATABLE, SAVE :: xp

as an alias for the unknowns to be linked at runtime (according to the
specifications of an input file, for example). For now, I just set
explicitly the pointers assignment for "test-driver" purposes (after
the proper sizing of the aforementioned array)

xp(1)%p => lvlv
xp(2)%p => ps
xp(3)%p => pc
xp(4)%p => mu
xp(5)%p => Tc

The unknown variables were defined as targets (alongside with others)

REAL(dp), TARGET :: mp, pmec, a, b, pmi, eta_is_c, eta_is_t, eta_m_t,
eta_m_c, Ts, rho, lvlv, ps, pc, mu, Tc

The array x stores the input unknowns values from the root-finding
algorithm routine. When I have to compute the values returned by the
functions containing the equations, I need to assign to the unknowns
the input values using the array of pointers as an alias for them. The
following statement is the only one I wrote that compiles correctly
(with g95)

DO i=1, SIZE(x)
xp = arr_ptr(x(i))
END DO

But unfortunately, at runtime, the pointed variables (lvlv, ps, pc,
mu, Tc) are not affected by the assignment statement and retain the
old values.

How could I select the unknowns at runtime undertaking the selecting
process just once in a "set_system" routine at the start of the
computations, and then referring to them by an alias?

Thank you.


Emanuele
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