equivalence tests for Fortran

equivalence.f90

program equivalence

 implicit none

 integer, parameter :: sp = selected_real_kind(6, 37)
 integer, parameter :: dp = selected_real_kind(15, 307)
 integer, parameter :: dp_int = selected_int_kind(16)
 integer, parameter :: hp_int = selected_int_kind(4)
 integer, parameter :: qp = selected_real_kind(33, 4931)

 character, dimension(8) :: res_string
 real(dp)                :: seventh_component
 real(sp)                :: weight
 integer(hp_int)         :: charge
 integer(hp_int)         :: particle_id

 EQUIVALENCE (charge,res_string(1)),(particle_id,res_string(3)),(weight,res_string(5)),(seventh_component,res_string(1))

 res_string(1) = char(0)
 res_string(2) = char(1)
 res_string(3) = char(0)
 res_string(4) = char(1)
 res_string(5) = char(0)
 res_string(6) = char(0)
 res_string(7) = char(0)
 res_string(8) = char(1)

print *, 'Writing after res_string setup'
print *, seventh_component, weight, charge, particle_id

seventh_component = 0

print *, 'Writing after seventh_component setup'
print *, seventh_component, weight, charge, particle_id

weight = 2.35098870E-38
charge = 256
particle_id = 256

print *, 'Writing after single elements setup'
print *, seventh_component, weight, charge, particle_id

end program equivalence

OK, ho capito, io lo avevo fatto in maniera diversa.

Io li accoppiavo così:

real(kind=16) :: whole
real(kind=8) :: first(2)
integer(kind=4) :: second(2)
integer :: P_ncmp=3
equivalence(whole,first)
equivalence(first(2),second)

ma é decisamente meno pratico e più faticoso.
Adesso vedo di capire, e settimana prossima cerchiamo di mettere tutto assieme.