Implementing linspace (using Subroutine) – FORTRAN

In Fortran, there is no built-in function called linspace like in some other programming languages.

However, you can easily create a similar functionality by writing a subroutine or a function that generates an array of equally spaced values.

Example

• In this example, the linspace subroutine takes four arguments: start, end, num, and result.
• It calculates the step size by dividing the range (end – start) by the number of values minus one (num – 1).
• Then, it fills the result array with equally spaced values using a loop.

subroutine linspace(start, end, num, result)
  implicit none
  real, intent(in) :: start, end
  integer, intent(in) :: num
  real, intent(out) :: result(num)
  real :: step
  integer :: i
  
  step = (end - start) / (num - 1)
  
  do i = 1, num
    result(i) = start + (i - 1) * step
  end do
end subroutine linspace

program linspace_example
  implicit none
  
  real :: start_val, end_val
  integer :: num_vals, i
  real, allocatable :: values(:)
  
  start_val = 0.0
  end_val = 1.0
  num_vals = 10
  
  allocate(values(num_vals))
  
  call linspace(start_val, end_val, num_vals, values)
  
  do i = 1, num_vals
    print *, values(i)
  end do
  
  deallocate(values)
  
end program linspace_example

Output

   0.00000000    
   0.111111104    
   0.222222209    
   0.333333313    
   0.444444418    
   0.555555582    
   0.666666687    
   0.777777791    
   0.888888896    
    1.00000000