Welcome to diffstruc’s documentation!

diffstruc is a Fortran library providing the framework for automatic diferentiation.

The code is provided freely available under the MIT License.

The documentation provided here does not intend to be an explanation of the theory behind automatic differentiation; many great resources exist online for this purpose.

An example of how to use the library is shown below:

program test_diffstruc
  use diffstruc
  implicit none

  type(array_type) :: x, y
  type(array_type), pointer :: f, xgrad

  call x%allocate([2,2,1], source=2.0) ! Allocate a 2x2 array with 1 sample
  call y%allocate([2,2,1], source=10.0) ! Allocate a 2x2 array with 1 sample
  call x%set_requires_grad(.true.)
  x%is_temporary = .false.
  y%is_temporary = .false.

  f => x * y + sin(x)
  write(*,*) 'Value of f:', f%val(:,1)

  ! Perform differentiation
  xgrad => f%grad_forward(x)
  write(*,*) 'Gradient of f w.r.t x:', xgrad%val(:,1)

  ! Clean up
  call f%nullify_graph()
  call xgrad%nullify_graph()
end program test_diffstruc