docs/appendix/acknowledgement.rst
.. _acknowledgements:
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Acknowledgments
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The numdifftools package was originally a translation of an adaptive numerical differentiation toolbox written in Matlab by John D'Errico [DErrico2006]_.
Numdifftools has as of version 0.9 been extended with some of the functionality
found in the statsmodels.tools.numdiff module written by Josef Perktold [Perktold2014]_.