# How to resolve the error “deselaers/logos/rwthaachenuniversity-whitegray not found” in beamer poster?

I was using the following code for preparation of a poster in Latex using TeXstudio 2.6.6

\documentclass[final,hyperref={pdfpagelabels=false}]{beamer}
\usepackage{grffile}
\usepackage{graphicx}
\mode<presentation>{\usetheme{I6pd2}}
\usepackage[english]{babel}
\usepackage[latin1]{inputenc}
\usepackage{amsmath,amsthm,amssymb,latexsym}
\boldmath
\usepackage[orientation=landscape,size=a0,scale=1.4,debug]{beamerposter}
\newcommand{\R}{{\mathbb R}}
\usepackage{array,booktabs,tabularx}
\newcolumntype{Z}{>{\centering\arraybackslash}X} % centered tabularx columns
\newcommand{\pphantom}{\textcolor{ta3aluminium}} % phantom introduces a vertical space in p formatted table columns??!!
\listfiles
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\graphicspath{{figures/}}
\title{\huge Comparisons of   $B_{row}$-splittings  of Matrices}
\author{ \vspace{.2cm} {\bf \large{ author}}\\ \vspace{.2cm} Research Supervisor- prof john\\ \vspace{.2cm} School of statistics}
\institute{institute name}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\newlength{\columnheight}
\setlength{\columnheight}{105cm}
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\begin{document}
\begin{frame}
\begin{columns}
\begin{column}{.49\textwidth}
\begin{beamercolorbox}[center,wd=\textwidth]{postercolumn}
\begin{minipage}[T]{.95\textwidth}  % tweaks the width, makes a new \textwidth
\parbox[t][\columnheight]{\textwidth}{
\begin{block}{INTRODUCTION}
In many practical problems we come across the problem of computing a
solution to a system of linear equations in $n$ unknowns \textcolor{blue}
{\begin{eqnarray}\label{eq0}
Ax=b,\end{eqnarray}
}
where $A$ is a real rectangular $m\times n$ matrix and $b$ is a real $m$-vector.
In a wide variety of such problems, including the Neumann problem  and those
for elastic bodies with free surfaces, the finite difference formulations lead to
a singular, consistent linear system (\ref{eq0}) where $A$ is large and sparse.
Here the general method of solution is iterative in nature. Iterative methods
where $A$ is rectangular or inconsistent, have been studied
in \cite{bpcones}. The authors  used generalized matrix
inverses for computing least square solutions in the inconsistent
\textcolor{blue}{
\begin{eqnarray}\label{eq01}
x^{(i+1)}=U^{\dag}Vx^{(i)}+U^{\dag}b,
\end{eqnarray}
}
where $U^{\dag}$ is the Moore-Penrose inverse of $U$.
\vspace{.5cm}
The above scheme is said to be convergent if the spectral radius of
$U^{\dag}V$ is less than 1. For a proper splitting, the authors of
\cite{bpcones} have shown that  $x=A^{\dag}b$ for any initial
vector $x^{0}$ if and only if (\ref{eq01}) is convergent.
\end{block}
\vfill
\begin{block}{PRELIMINARIES}
\textcolor{darkgreen}{Moore-Penrose inverse}\\
The  Moore-Penrose inverse of $A\in {\R}^{m\times n}$
is the unique matrix $A^{\dag}\in {\R}^{n\times m}$ that satisfies the following four
equations:
$$AA^{\dag}A=A,~~~~A^{\dag}AA^{\dag}=A^{\dag},~~~~(AA^{\dag})^{T}=AA^{\dag}~~\mbox{and} ~~(A^{\dag}A)^{T}=A^{\dag}A.$$
If $A^{\dag}\geq 0$, then it is semimonotone. Berman and Plemmons, \cite{bpmonotono}
showed that
$A^{\dag}\geq 0$  if and only if $Ax\in {\R}^m_+ +N(A^T) ~~\mbox{and}~~x \in R(A^{T})$ imply  $x\geq 0.$

\textcolor{darkgreen}{Row monotone matrix}\\
$A\in {\R}^{m\times n}$ is said to be row monotone \cite{bpmonotono} if  $Ax\geq 0 ~~\mbox{and}~~x \in R(A^{T})$ imply  $x\geq 0.$ \\

$A$ is row monotone if and only if $A$ is
$\{1,4\}$-monotone. ($\{1,4\}$-monotone means there is a nonnegative $G$ satisfying
$AGA=A$ and $(GA)^T=GA$.)
If $A^{\dag} \geq 0$,  then $A$ and $A^T$ are  row monotone.
However, the converse is not true. \\

A  decomposition $A=U-V$ of $A\in {\R}^{m\times n}$ is called
\textcolor{blue}{{\it positive}}  if $U\geq 0$ and $V\geq 0$. \\
\vspace{.2cm}

\textcolor{darkgreen}{ $B_{row}$-splitting (Definition 2.6, \cite{mis})}\\
A positive   proper splitting $A=U-V$ of $A\in {\R}^{m\times n}$ is called a $B_{row}$-
splitting if it satisfies the following conditions: \\
(i) $VU^{\dag}\geq 0$, and \\
(ii) $Ax,~ Ux\geq 0 ~~\mbox{and}~~x \in R(A^{T})$ imply  $x\geq 0.$\\

\vspace{.2cm}
\textcolor{darkgreen}{Theorem 1} (Theorem 2.7, \cite{mis})\\
Let $A\in {\R}^{m\times n}$. Suppose that $R(A) \cap int(\mathbb{R}^m_+) \neq \emptyset$. Consider the following statements:\\
(a) $A$ is row monotone.\\
(b) ${\R}_{+}^{m}\cap R(A) \subseteq A{\R}_{+}^{n}$.\\
(c) There exists $x^{0}\in {\R}_{+}^{n}$ such that $Ax^{0} \in int({\R}_{+}^{m})$.\\
Then, we have (a) $\Rightarrow$ (b) $\Rightarrow$ (c).\\
Suppose that $A$ has a $B_{row}$-splitting. Then each of the above is equivalent to the
following:\\
(d) $\rho(VU^{\dag})<1$.

\vspace{.2cm}

\textcolor{darkgreen}{Theorem 2} (Theorem 2.12, \cite{mis})\\
Suppose that $A$ is row monotone and $R(A) \cap int({\R}^{m}_{+}) \neq \emptyset$ for
$A\in {\R}^{m\times n}$.
Further, let $A^{\dag}A\geq 0$. Then $A$ possesses a  $B_{row}$-splitting $A=U-V$  with
$\rho(VU^{\dag})<1$.
\end{block}
\vfill
\begin{block}{OBJECTIVE}
To  present a more general
convergence theorem for $B_{row}$-splitting and to  compare two $B_{row}$-splittings.
\end{block}
}
\end{minipage}
\end{beamercolorbox}
\end{column}
% ---------------------------------------------------------%
% end the column

% ---------------------------------------------------------%
% Set up a column
\begin{column}{.49\textwidth}
\begin{beamercolorbox}[center,wd=\textwidth]{postercolumn}
\begin{minipage}[T]{.95\textwidth} % tweaks the width, makes a new \textwidth
\parbox[t][\columnheight]{\textwidth}{ % must be some better way to set the the height, width and textwidth simultaneously
% Since all columns are the same length, it is all nice and tidy.  You have to get the height empirically
% ---------------------------------------------------------%
% fill each column with content

\begin{block}{MAIN RESULTS}
We begin with the following lemma which is useful to prove our main results of this section.
\vspace{.4cm}
\textcolor{yellow}{LEMMA 3}\\
\textcolor{blue}{(a) If $A$ is row monotone, $V\geq 0$ and $R(V)\subseteq R(A)$, then
$A^{\dag}V\geq 0$.\\
(b) If $A^T$ is row monotone, $V\geq 0$ and $N(A)\subseteq N(V)$, then $VA^{\dag}\geq 0$.}

\vspace{.4cm}
Now, we obtain a new  convergence theorem for  $B_{row}$-splittings which holds
even without the assumption $R(A) \cap int({\R}^{m}_{+}) \neq \emptyset$. Thus, the
present one is more general  than the earlier one (Theorem 2).

\vspace{.4cm}
\textcolor{yellow}{THEOREM  4}\\
\textcolor{blue}{ Let  $A=U-V$ be a  $B_{row}$-splitting of $A\in {\R}^{m\times n}$. If
$A$ is row monotone,then\\
(a) $A^{\dag}\geq U^{\dag}$;\\
(b) $\rho(VA^{\dag})\geq \rho(VU^{\dag})$;\\
(c) $\rho(VU^{\dag})=\rho(U^{\dag}V)=\frac{\rho(A^{\dag}V)}{1+\rho(A^{\dag}V)}<1$.}

\vspace{.4cm}
Theorem 2 enables us that there exist several $B_{row}$-splittings of a given matrix.
In this direction, we  present  two comparison theorems for  $B_{row}$-splittings.

\vspace{.4cm}
\textcolor{yellow}{THEOREM 5}\\
\textcolor{blue}{ Let  $A=U_{1}-V_{1}=U_{2}-V_{2}$ be two  $B_{row}$-splittings of
$A$. If  $A$ is  row monotone and $V_{2}\geq V_{1}$, then
$$1> \rho(U_{2}^{\dag}V_{2}) \geq \rho(U_{1}^{\dag}V_{1}).$$}

\vspace{.4cm}
\textcolor{yellow}{EXAMPLE 6 }
Let $A=\left( \begin{array}{cc} 1 & 1 \\ 1 & 1 \\ \end{array} \right)$. Clearly $A$ is row monotone. Setting
$U_{1}=3A$ and $U_{2}=4A$.  We  then have $0\leq V_{1}=2A\leq 3A=V_{2}$.  Hence
$\rho(V_{1}U_{1}^{\dag})=\frac{2}{3}\leq \frac{3}{4}=\rho(V_{2}U_{2}^{\dag})<1$.

\vspace{.4cm}
The condition $V_2\geq V_1$ can not be dropped. For example, set $V_{1}=3A$ and
$V_{2}=2A$.Then the implication $$\rho(U_{1}^{\dag}V_{1}) \leq \rho(U_{2}^{\dag}V_{2}) < 1$$ does not hold. Similarly,the assumption  $U_{1}^{\dag}\geq U_{2}^{\dag}$ in the
Theorem given below can not be dropped.

\vspace{.4cm}
\textcolor{yellow}{THEOREM 7}\\
\textcolor{blue}{ Let $A\in {\R}^{m\times n}$ be such that $A$ and $A^T$ are row
monotone. Let $A=U_{1}-V_{1}=U_{2}-V_{2}$ also be   two  $B_{row}$-splittings of
$A$.  If $U_{1}^{\dag}\geq U_{2}^{\dag}$,then $$1>\rho(U_{2}^{\dag}V_{2}) \geq \rho(U_{1}^{\dag}V_{1}).$$ }
\end{block}
\vfill
\begin{block}{CONCLUSIONS}
A convergence theorem and comparison theorems for  $B_{row}$-splittings are presented.
\end{block}
\vfill
\begin{block}{PUBLICATIONS}
{Jena, L. and Mishra, D.},
\emph{Comparisons of   $B_{row}$-splittings and $B_{ran}$-splittings of Matrices},
Linear and Multilinear Algebra, DOI 10.1080/03081087.2012.661426
\end{block}
\vfill
\begin{block}{ACKNOWLEDGEMENTS}
I thank my research supervisor  prof. john    for his  encouragement.
\end{block}
\vfill
\begin{block}{REFERENCES}

\begin{thebibliography}{10}
\bibitem{bpcones} {Berman, A.; Plemmons, R. J.},
\emph{Cones and iterative methods for best square least squares solutions of linear
systems},SIAM J. Numer. Anal., 11 (1974) 145-154.

\bibitem{bpmonotono} {Berman, A.; Plemmons, R. J.},
\emph{Monotonicity and the generalized inverse},SIAM J. Appl. Math.  22 (1972) 155-161.

\bibitem{mis} {  Mishra, D.;  Sivakumar, K. C.},
\emph{Generalizations of matrix monotonicity and their relationships with
certain subclasses of proper splittings},
Linear Algebra Appl. DOI:10.1016/j.laa.2011.11.016 .

\bibitem{per} {Peris, J. E.},
\emph{A new characterization of inverse-positive matrices},
Linear Algebra Appl.  154/156  (1991) 45-58.

\bibitem{var} {Varga, R. S.},
\emph{Matrix Iterative Analysis},  Springer-Verlag, Berlin, 2000.

\end{thebibliography}
\end{block}
}
\end{minipage}
\end{beamercolorbox}
\end{column}
% ---------------------------------------------------------%
% end the column
\end{columns}
\end{frame}
\end{document}


I am getting the following errors

File deselaers/logos/rwthaachenuniversity-whitegray' not found.
Package xcolor Error: Undefined color darkgreen' \end{frame}
Package xcolor Error: Undefined color darkgreen' \end{frame}
Package xcolor Error: Undefined color darkgreen' \end{frame}
Package xcolor Error: Undefined color darkgreen' \end{frame}
Package xcolor Error: Undefined color darkgreen' \end{frame}
File deselaers/logos/rwthaachenuniversity-whitegray' not found. \end{frame}


I don't know why these errors are there. I need the help of experts.

-

Be sure to have the latest version of beamerthemeI6pd2.sty downloadable at https://github.com/jtanderson/Fish-Poster/blob/master/beamerthemeI6pd2.sty.

Then pass the option svgnames to xcolor through beamer, that means load beamer as

\documentclass[final,hyperref={pdfpagelabels=false},xcolor={svgnames}]{beamer}


After that, replace all instances of darkgreen with DarkGreen in your document and it should compile fine.

@Litun put the line \setbeamercolor*{normal text}{fg=tachameleon, bg=ta3gray} in your document and change ta3gray to whatever you like. The document is already in a0 landscape size. BTW. remember that you can accept (and upvote) the answer if it helped you. – karlkoeller Feb 7 '14 at 15:41
@Litun for example the ones you find in the xcolor` documentation, section 4.3, p.38. – karlkoeller Feb 7 '14 at 15:55