# Loading xdmf data back in **URL:** \ **Category:** I/O\ **Created:** [November 19, 2019, 1:45am UTC](https://fenicsproject.discourse.group/t/loading-xdmf-data-back-in/1925 "2019-11-19T01:45:48Z")\ **Posts on this page:** 1\ **Showing post:** 21
**Author:** ![Ben\_Bird](https://yyz2.discourse-cdn.com/free1/user_avatar/fenicsproject.discourse.group/ben_bird/32/3204_2.png) [@Ben\_Bird](https://fenicsproject.discourse.group/u/Ben_Bird)\ **Post date:** [February 14, 2022, 9:50pm UTC](https://fenicsproject.discourse.group/t/loading-xdmf-data-back-in/1925/21 "2022-02-14T21:50:30Z")
Hi there, Having successfully imported time averaged functions for the velocity and pressure fields, I was wondering if there was a way to interpolate these to a mixed element function space. The purpose of doing so is to extract the Jacobian matrix via the process outlined in: > [@Navier-Stokes, stability, Jacobian and eigenvalues](https://fenicsproject.discourse.group/t/navier-stokes-stability-jacobian-and-eigenvalues/1833/2): > > In case anyone has the same problem, I had a similar issue and solved it on my end. On the subject of boundary conditions, my understanding of the problem is that under the hood, when a DirichletBC is specified at assembly, dolfin cancels the rows and columns associated with the relevant degrees of freedom, then set its diagonal terms to 1. In other words, given a boundary \Gamma it modifies A so that Ax=b also imposes x\_\Gamma=b\_\Gamma Another very important physical thing about the code abov… Any help would again be much appreciated, Thanks, Ben --- _[View the full topic](https://fenicsproject.discourse.group/t/loading-xdmf-data-back-in/1925)._