How do I get the inverse of matrix D when estimating displacement field(D) that aligns two 2-D images?

Hi, I am using this demo for my project https://www.mathworks.com/help/images/ref/imregdemons.html?searchHighlight=non%20linear%20transform%20image&s_tid=doc_srchtitle

but was wondering how to calculate the inverse of the matrix D that the command imregdemons outputs.