\documentclass{article} \usepackage[all]{xy} \usepackage{amsmath,xcolor} \newcommand{\lambdabar}{{\mkern0.75mu\mathchar '26\mkern -9.75mu\lambda}} \begin{document} \noindent \pagestyle{empty} \huge \[ 	\xymatrix@C=0.5em@R+1em{ 	& \underset{_{\substack{\text{linear}\\\text{wavenumber}}}}{\tilde{\nu}} 	\ar^-{_{\color{gray}x \cdot \tau}}[rr] 	\ar^>>>>>>>>>>>>>>>>>>>>{\color{gray}\frac{1}{x}}@{<.>}[dd] 	\ar_-{_{\color{gray}x \cdot v_p}}[dl] 	& 	& \underset{_{\substack{\text{angular}\\\text{wavenumber}}}}{k} 	\ar^-{_{\color{gray}x \cdot v_p}}[dl] 	\ar^-{\color{gray}\frac{1}{x}}@{<->}[dd] 	\\ 	\underset{_{\substack{\text{linear}\\\text{frequency}}}}{f} 	\ar^{_{\color{gray}\qquad\;\; x \cdot \tau}}[rr] 	& 	& \underset{_{\substack{\text{angular}\\\text{frequency}}}}{\omega} 	\ar^>>>>>>>>>>>>>>>>>>>>{\color{gray}\frac{1}{x}}@{<->}[dd] 	\\ 	& \underset{_{\substack{\text{linear}\\\text{wavelength}}}}{\lambda} 	\ar^-{_{\qquad\quad\color{gray}x/\tau}}@{.>}[rr] 	\ar^>>>>>>>>>>>>>>>{_{\color{gray}x / v_p}}@{.>}[dl] 	& 	& \underset{_{\substack{\text{angular}\\\text{wavelength}}}}{\lambdabar} 	\ar^-{_{\color{gray}x / v_p}}[dl] 	\\ 	\underset{_{\substack{\text{linear}\\\text{period}}}}{T} 	\ar^-{\color{gray}\frac{1}{x}}@{<->}[uu] 	\ar^-{_{\color{gray}x / \tau}}[rr] 	& 	& \underset{_{\substack{\text{angular}\\\text{period}}}}{?} 	} \]  \vspace{1em} \Large  $v_p =$ wave speed (phase velocity)  $\tau = 2\pi$ \end{document}