Re: [Plplot-devel] Support arbitrary storage of 2D user data

[Arjen M. <arj...@de...>]

Hi,

I have been studying the source code for the Fortran bindings and the
aribtrary storage facility and my conclusion is:
- The bindings will benefit internally because we do no longer have to
   create a transposed array in the C fashion.
- I can create a binding for the most flexible functions (plfcont and
   plfshade(s) so that a user can supply his/her own data structure.
   It will take some interface juggling in Fortran 90/95, as that is
   more strict than FORTRAN 77. (Some technical details are involved
   here)

I first thought it would be a flexibility that would "never" be used
in practice (2D arrays being the most common form of storing such data
in Fortran), but consider this:
We do not have to store a complete set of data! Instead we could also
use the retrieval function to get the value of a function - something
along these lines:

     real(PLFLT) function f(i, j, params )
         integer :: i, j
         real(PLFLT) :: params

         real(PLFLT) :: x, y
         ... compute x and y from i and j and params
         f = x**2 + y**2
     end function f

or to transform the data:

     real(PLFLT) function logf(i, j, data )
         integer :: i, j
         type(userdata) :: data

         logf = log(data%value(i,j))
     end function logf

(I am not quite sure how to transfer the array dimensions yet - hence
the impromptu derived type)

Regards,

Arjen


On 2010-10-12 17:55, Hazen Babcock wrote:
> Arjen Markus wrote:
>> Hi David, Hazen,
>>
>> I will have a look at propagating those functions to FORTRAN 77 and
>> Fortran 90/95.
>>
>> Regards,
>>
>> Arjen
> 
> Thank you both for volunteering :).
> 
> -Hazen
> 
> 
 

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