# 1.7 Acknowledgments

Pyxplot builds on ideas from several pre-existing open-source software projects. We like gnuplot’s simple and intuitive interface, and Pyxplot’s command syntax is intentionally very similar, to the point of backwards compatibility in many cases. Even when designing the entirely new parts of Pyxplot’s syntax, we have followed gnuplot’s preference for short simple command-line syntax. Early versions of Pyxplot utilised the PyX graphics library for Python, and we have borrowed many ideas from it in our new output engine.

Several people have contributed code to Pyxplot. Michael Rutter provided us with a copy of his public domain code for converting bitmap images into PostScript, which we used in the implementation of the `image` command and the `colormap` plot style. Matthew Smith provided C implementations of the Airy functions and the Riemann zeta function for general complex inputs, and helped test Pyxplot’s mathematical environment. Zoltán Vörös worked on our development team from 2010 until 2011. John Walker has published public domain code implementing RGB rendering of the electromagnetic spectrum, which we use in the `colors.wavelength()` function.

We would also like to thank all the users who have got in touch with us by email since Pyxplot was first released on the web in 2006. Your feedback and suggestions have been gratefully received.

Final thanks go to our team of alpha testers, without whose work Pyxplot would doubtless still contain many more bugs. Especial thanks go to Rachel Holdforth and Stuart Prescott.