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simon
Joined: 05 Jul 2006
Posts: 270
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 Posted: Mon Feb 06, 2023 7:06 pm Post subject: |
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I was pleased to see that Source= has become available for the allocate statement. But when I get a rather unclear error message for the following code:
| Code: | Module m
Integer, Dimension(:), Allocatable :: a
Integer, Dimension(5) :: b
End Module m
!
Program p
Use m
Allocate (a, Source=b)
End Program p |
When the documentation qualifies "for arrays only" what exactly does that mean? |
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PaulLaidler
Site Admin
Joined: 21 Feb 2005
Posts: 8011
Location: Salford, UK
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| Posted: Tue Feb 07, 2023 8:51 am Post subject: |
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Simon
Your code reveals a bug in the new FTN95 feature. At the moment it doesn't work when the arrays are declared in a module. I will log this as a bug that needs fixing.
The new feature has not yet been programmed for scalars so the following code will fail at runtime.
| Code: | integer,allocatable::a
integer::b
b = 7
Allocate(a, source=b)
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PaulLaidler
Site Admin
Joined: 21 Feb 2005
Posts: 8011
Location: Salford, UK
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| Posted: Tue Feb 07, 2023 9:28 am Post subject: |
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Simon
The failure for arrays declared in a module has now been fixed for the next release of FTN95. |
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simon
Joined: 05 Jul 2006
Posts: 270
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| Posted: Tue Feb 28, 2023 9:06 pm Post subject: |
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| Could we please get Nint, Aint and Anint added to the list of intrinsic functions that can be used in an initialisation expression. |
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PaulLaidler
Site Admin
Joined: 21 Feb 2005
Posts: 8011
Location: Salford, UK
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| Posted: Wed Mar 01, 2023 9:07 am Post subject: |
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Simon
Thanks. These have now been added for the next release of FTN95. |
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Kenneth_Smith
Joined: 18 May 2012
Posts: 709
Location: Hamilton, Lanarkshire, Scotland.
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| Posted: Fri Mar 24, 2023 12:42 pm Post subject: |
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Earlier in this discussion we talked about exactly what the ASSOCIATE construct does.
Following its recent addition to FTN95, the program below which uses the trapezoidal method to integrate a set of data points can now be compiled successfully and run.
I find the *three* lines of code that define the trapezoidal method rather mind blowing!
An very interesting and educational example, which I thought was worth sharing.
| Code: | program p
implicit none
integer, parameter :: n = 101
double precision x(n), y(n), r1(n), omega
integer i
omega = 2.d0*4.d0*atan(1.d0)*50.d0
forall (i=1:n) x(i) = (i-1)/5000.d0 ! x
forall (i=1:n) y(i) = cos(omega*x(i)) ! f(x)
forall (i=1:n) r1(i) = integrate(x(1:i),y(1:i)) ! Integral of f(x).dx
r1 = omega*r1 ! Normalise integral
i = winio@('%pl[native,frame,x_array,n_graphs=1,width=2,y_max=1,Title="f(x)"]&', 600,300,n,x,y)
i = winio@('%ff&')
i = winio@('%pl[native,frame,x_array,n_graphs=1,width=2,y_max=1,Title="Omega * Integral of f(x)"]', 600,300,n,x,r1)
contains
pure function integrate(x, y) result(r)
!! Calculates the integral of an array y with respect to x using the trapezoid
!! approximation. Note that the mesh spacing of x does not have to be uniform.
!!
!! Source: https://fortranwiki.org/fortran/show/integration
!!
double precision, intent(in) :: x(:) !! Variable x
double precision, intent(in) :: y(size(x)) !! Function y(x)
double precision :: r !! Integral y(x)�dx
! Integrate using the trapezoidal rule
associate(n => size(x))
r = sum((y(1+1:n-0) + y(1+0:n-1))*(x(1+1:n-0) - x(1+0:n-1)))/2.d0
end associate
end function
end program p
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