# [Tex/LaTex] Alignment of entries in matrix

horizontal alignmentmatrices

I have this pmatrix (amsmath package):

\documentclass{article}
\usepackage{amsmath}

\begin{document}
$$\begin{pmatrix} \frac{a}{b} & \frac{a}{b} & 0 & 1-\frac{a}{b} \\ 0 & 0 & -1 & 0 \\ c-\frac{a}{b} & c-\frac{a}{b} & 0 & \frac{a}{b} \\ d+c-\frac{a}{b} & d+c-\frac{a}{b} & 0 & -\frac{a}{b} \end{pmatrix}$$
\end{document}


I'd like to align entries of the matrix so all fractions are aligned. Is there a way to to this within the pmatrix environment, or do I have to use \begin{array}?

The mathtools package allows to adjust the alignment of matrix elements:
\documentclass{article}
$$\begin{pmatrix*}[r] \frac{a}{b} & \frac{a}{b} & 0 & 1-\frac{a}{b} \\ 0 & 0 & -1 & 0 \\ c-\frac{a}{b} & c-\frac{a}{b} & 0 & \frac{a}{b} \\ d+c-\frac{a}{b} & d+c-\frac{a}{b} & 0 & -\frac{a}{b} \end{pmatrix*}$$