Found the problem: "double precision" on my machine (presumably, any 64-bit
machine) with "-fdefault-real-8" flag will be "real*16" (something like
non-existent "Float128" in Julia).
On Wednesday, November 9, 2016 at 4:05:59 PM UTC+2, Alexey Cherkaev wrote:
>
> On a smaller example I can see that it is indeed is because floats are not
> double floats.
>
> It's seem to be the statement
>
> implicit double precision (a-h,o-z)
>
> in Fortran code that throws things upside down. I'm not so familiar with
> the Fortran standard and especially with gfortran extensions, but I would
> think if anything, this statement would force the arguments to be double
> float (real*8) precision. Also, I put "-fdefault-real-8" option to the
> compiler...
>
> But thanks for the tip, perhaps I would just comment this statement out in
> Fortran.
>
>
> On Wednesday, November 9, 2016 at 3:49:55 PM UTC+2, Ángel de Vicente wrote:
>>
>> Hi,
>>
>> Alexey Cherkaev <alexey....@gmail.com> writes:
>> > To cut long story short, I have a problem of passing floating-point
>> numbers from
>> > Julia to Fortran subroutine. Documentation suggests, that each
>> parameter to
>> > Fortran's program needs "Ref{T}" wrapper as they are passed by
>> reference (I've
>> > seen that older code also uses Ptr{T} with "&" at variable names). It
>> works fine
>> > for integers (I even can see the difference if "FInt" alias is changed
>> between
>> > "Int32" and "Int64" and if "-fdefault-integer-8" in compiling option is
>> present
>> > or omitted). But I don't see a single floating point value passed
>> correctly
>> > (including floating-point arrays). I've also tried, as an extreme
>> measure, to
>> > pass a floating point parameter as a vector (of size 1) and have a
>> corresponding
>> > type in ccall to be "Ptr{Float64}"
>>
>> Perhaps in Fortran you have 32bits floats? I just tried with this, and I
>> have no problem passing floats to Fortran:
>>
>> ,----
>> | testdp(ar) = ccall((:__tests_MOD_testdp, "./testmodgfort"),Float64,
>> (Ptr{Float64},), &ar)
>> | println("Result of function call to Fortran ", testdp(5.0))
>> `----
>>
>> ,----
>> | DOUBLE PRECISION FUNCTION testdp (a)
>> | DOUBLE PRECISION :: a
>> | testdp = 5.0*a
>> | END FUNCTION testdp
>> `----
>>
>> ,----
>> | julia> include("julia-fortran.jl")
>> | Result of function call to Fortran 25.0
>> `----
>>
>> --
>> Ángel de Vicente
>> http://www.iac.es/galeria/angelv/
>>
>
