LaTeXで1未満の10進小数を2進数へ変換

(0.1875)_10 = (0.0011)_2の変換の様子をLaTeXで実現する．

test.tex

\documentclass{article}

\usepackage{xstring}
\usepackage{xifthen}

\usepackage{amsmath}

\usepackage{fp}

\begin{document}


\newcounter{index}

\newcommand{\FtoB}[2][2]{%
   \edef\result{#2}%
   \FPsub{\result}{\result}{0}%
   \edef\resbin{0.}%
   \StrLen{#2}[\mystrlen]%
   \setcounter{index}{0}%
   \FPsub{\mylen}{\mystrlen}{2}%
   \FPtrunc{\result}{\result}{\mystrlen}%
   \whiledo{\value{index} < \mystrlen}{%
      \stepcounter{index}%
      $\result * 2 = {}$%
      \FPmul{\result}{\result}{2}%
      \FPtrunc{\resultint}{\result}{0}%
      \FPsub{\result}{\result}{\resultint}%
      \FPtrunc{\result}{\result}{\mystrlen}%
      \edef\resbin{\resbin\resultint}%
      $\result \rightarrow$ \ \resultint, \resbin
      \\
   }
}



\noindent
\FtoB{0.1875}

\noindent
\FtoB{0.5}

\noindent
\FtoB{0.125}

\noindent
\FtoB{0.25}

\noindent
\FtoB{0.200000000}


\end{document}

こうなります．