Hi,
When I tried the following Fortran routine (abc.f), it worked using the
following shared file and ccall.
But when I tried after changing DOUBLE PRECISION with REAL, it did not
work. How should it be fixed.
This is what I saw on the Internet and worked:
abc.f file I saw on the Internet
SUBROUTINE MULTIPLY(A,B,C)
DOUBLE PRECISION A,B,C
C = A*B
RETURN
END
gfortran abc.f -o abc.so -shared -fPIC
a = 2.0
b = 4.2
n = Float64[1.0]
ccall((:multiply_, "abc.so"), Void,
(Ptr{Float64},Ptr{Float64},Ptr{Float64}),&a,&b, n)
julia> n
1-element Array{Float64,1}:
8.4
Again ccall worked with DOUBLE PRECISION.
When I used REAL like the following:
SUBROUTINE MULTIPLY(A,B,C)
DOUBLE PRECISION A,B,C
C = A*B
RETURN
END
and used the same procedure like
gfortran abc.f -o abc.so -shared -fPIC
a = 2.0
b = 4.2
julia> n = Array(Float64)
0-dimensional Array{Float64,0}:
0.0
julia> ccall((:multiply_, "abc.so"), Void,
(Ptr{Float64},Ptr{Float64},Ptr{Float64}), &a, &b, n)
julia> n
0-dimensional Array{Float64,0}:
1.061e-314
The default value of 0.0 changed to 1.061e-314, which is not the correct
answer.
When I assigned a specific number to n:
julia> n = Float64[1.0]
1-element Array{Float64,1}:
1.0
julia> ccall((:multiply_, "abc.so"), Void,
(Ptr{Float64},Ptr{Float64},Ptr{Float64}), &a, &b, n)
Then the array element value was not changed.
julia> n
1-element Array{Float64,1}:
1.0
I am wondering why it does not work with REAL variables.
I tried Logical, Int, and Character variables, along with Double Precision.
All worked, except for REAL.
Thanks,
On Sunday, May 31, 2015 at 8:53:15 PM UTC-4, Eduardo Lenz wrote:
>
>
> Hi
> I am using the dsplp subroutine (Linear Programming) from LINPACK. It is
> also in FORTRAN and I made a simple interface to use it in Julia. Although
> the data format used internally by the dsplp subroutine is diferent, I made
> the following function in julia to emulate the linpro package from Scilab
> (without the equality constraint, but it can be changed).
>
> The julia function is
>
> <script src="https://gist.github.com/anonymous/9e4bcda40a5e66f9f104.js
> "></script>
>
> and the fortran subroutine is
>
> <script src="https://gist.github.com/CodeLenz/223f3efe4b9e386059e2.js
> "></script>
>
> To generate the .so, I use this fortran subroutine and some of the fortran
> functions from LINPACK;
>
> The usage is simple like this
>
> function Linpro_Test()
>
> # Min 2x[1] + 3x[2]
> # S.T
> # -x[1] - x[2] <= -1.0
> #
> # 0<= x[1] <= 5
> # 0<= x[2] <= 5
> #
> # Solution x = [1,0]
>
> n = 2
> m = 1
> p = [2.0, 3.0]
> C = [-1.0 -1.0]
> b = [-1.0]
> ci = [0.0 , 0.0]
> cs = [5.0 , 5.0]
>
> x,lagr,info = Linpro_Slatec(n,m,p,C,b,ci,cs)
>
> println("\n Result ",x)
> println("\n Lagr ",lagr)
> println("\n Info ",info)
>
> end
>
>
>
> On Saturday, May 30, 2015 at 10:52:03 PM UTC-3, Jiahao Chen wrote:
>>
>> It would be great if you could clean up your example and add it to the
>> documentation.
>>
>> Thanks,
>>
>> Jiahao Chen
>> Research Scientist
>> MIT CSAIL
>>
>> On Sun, May 31, 2015 at 3:17 AM, Andre Bieler <[email protected]>
>> wrote:
>>
>>> Ok so I have a few simple examples working for ccalling fortran
>>> functions and subroutines from Julia.
>>> Maybe someone will find this useful examples when first looking into
>>> calling fortran from julia.
>>>
>>> compile the following fortran mod
>>> ```
>>> !fileName = simplemodule.f95
>>> module simpleModule
>>>
>>> implicit none
>>>
>>> contains
>>> function foo(x)
>>> integer :: foo, x
>>> foo = x * 2
>>> end function foo
>>>
>>> subroutine bar(x, a, b)
>>> integer, intent(in) :: x
>>> integer, intent(out) :: a, b
>>>
>>> a = x + 3
>>> b = x * 3
>>> end subroutine bar
>>>
>>> subroutine keg(x, a, b)
>>> real*8, intent(in) :: x
>>> real*8, intent(out) :: a, b
>>>
>>> a = x + 3.0
>>> b = x * 3.0
>>> end subroutine keg
>>>
>>> subroutine ruf(x, y)
>>> real*8, dimension(3), intent(in) :: x
>>> real*8, dimension(3), intent(out) :: y
>>> integer :: i
>>>
>>> DO i = 1, 3
>>> y(i) = 2*x(i)
>>> END DO
>>> end subroutine ruf
>>>
>>> end module simplemodule
>>> ```
>>>
>>
>>
