\documentclass[a4paper]{article}

\usepackage{pgfplots}

\begin{document}

\begin{tikzpicture}
%\tracingcommands=2\tracingmacros=2
	\begin{axis}
	\addplot3[
		surf,
		shader=interp,
		domain=0:1,
		mesh/color input=explicit mathparse,
		mesh/colorspace explicit color input=wave,
		point meta/symbolic={363+x*(814-363)},
	]
	{x*y};
	\end{axis}
\end{tikzpicture}
\end{document}

