  The Fast Fourier Transform (FFT) is a numerical operation that transforms a
function into a form comprised of its constituent frequencies and is an
integral part of scientific computation and data analysis. The objective of our
work is to enable use of the FFT as part of a scientific in situ processing
chain to facilitate the analysis of data in the spectral regime. We describe
the implementation of an FFT endpoint for the transformation of
multi-dimensional data within the SENSEI infrastructure. Our results show its
use on a sample problem in the context of a multi-stage in situ processing
workflow.
