Switching from standalone to beamer gives an error

Question

I'm trying to modify the below code and use it in beamer instead of standalone, however, when I switch the document class to beamer I get an error "illegal parameter number..this part of the code is giving the error

  \newcommand{\positionXOnEl}[3]{%
    \pgfmathsetmacro{#1}%
      {\figYOrigin+#2*%
      \figBEll*((1-#3^2/\figAEll^2)^2)^(0.25)}}
  \newcommand{\positionYOnEl}[3]{%
    \pgfmathsetmacro{#1}%
      {#2*((\figBEll^2-\figYOrigin^2+2*\figYOrigin*#3-#3^2)^2)^(0.25)*(\figAEll/\figBEll)}}

although it is only a new command.

 %\documentclass[tikz]{standalone}
\documentclass[9pt,aspectratio=169,xcolor=table]{beamer}
\usepackage{pgfplots}
\usepackage{amsmath}
\usepackage{tikz-3dplot}
\pgfplotsset{compat=1.14}
\tikzset{>=latex}
\begin{document}
\begin{frame}
% !TEX root = ../main.tex
\tdplotsetmaincoords{60}{100}
\begin{tikzpicture}[scale=0.75,tdplot_main_coords]
  % DEFINITIONS
  % figOmegaRotation : Value for the Omega angle
    \pgfmathsetmacro{\figOmega}{33}
  % figIRotation : value for inclination of the orbital plane
    \pgfmathsetmacro{\figIRotation}{30}
  % \figAEll : minimum value for ellipse
    \pgfmathsetmacro{\figAEll}{2.5}
  % \figBEll : minimum value for ellipse
    \pgfmathsetmacro{\figBEll}{3}
  % figYOrigin : focus of the ellipse with 2.5 and 3
    \pgfmathsetmacro{\figYOrigin}{sqrt(\figBEll^2 - \figAEll^2)}
    % sqrt(b^2 - a^2)
% COMMANDS
  % \positionOnEl{\storing}{\quadrant}{\x}
  % Saves into \storing the position \y on the ellipse
  % specified by \figAEll and \figBEll. \quadrant should help
  % in defining the quadrant (must be +1 or -1)
  \newcommand{\positionXOnEl}[3]{%
    \pgfmathsetmacro{#1}%
      {\figYOrigin+#2%
      \figBEll((1-#3^2/\figAEll^2)^2)^(0.25)}}
  \newcommand{\positionYOnEl}[3]{%
    \pgfmathsetmacro{#1}%
      {#2((\figBEll^2-\figYOrigin^2+2\figYOrigin#3-#3^2)^2)^(0.25)(\figAEll/\figBEll)}}
\end{tikzpicture}
\end{frame}
\end{document}