# Higher Derivatives of fStress. Who Needs Them ?
Jan de Leeuw
Version 01, July 20, 2017
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Note: This is a working paper which will be expanded/updated frequently. All suggestions for improvement are welcome. The directory [gifi.stat.ucla.edu/third](http://gifi.stat.ucla.edu/third) has a pdf version, the bib file, the complete Rmd file with the code chunks, and the R and C source code.
#Introduction
The multidimensional scaling loss function fStress is defined as
\begin{equation}\label{E:fstress}
\sigma(x):=\mathop{\sum\sum}_{1\leq i