# Why can't I vertically align these two matrices?

Why won't these matrices become left-aligned?

\documentclass[11pt,a4paper,oneside]{report}
\usepackage[pdftex]{graphicx}
\usepackage[T1]{fontenc}
\usepackage{fouriernc}
\usepackage{mathtools}
\usepackage{amsfonts,amsmath,amssymb,amsthm}
\usepackage[a4paper, hmargin={3.5cm,3cm}, vmargin={2.5cm,2.5cm}]{geometry} % margin
\usepackage{multicol}

\begin{document}
\begin{align*}
&\renewcommand\arraystretch{1.4}
\begin{bmatrix}
a_{1}&u_{2}&\frac{a_{1}}{d}u_{3}\\
a_{2}&u_{1}&\frac{a_{2}}{d}u_{3}\\
a_{3}&0&u_{4}\\
\end{bmatrix}\\
\intertext{with}
&\renewcommand\arraystretch{1.4}
\begin{vmatrix}
a_{1}&u_{2}&\frac{a_{1}}{d}u_{3}\\
a_{2}&u_{1}&\frac{a_{2}}{d}u_{3}\\
a_{3}&0&u_{4}
\end{vmatrix}=1
\end{align*}
\end{document}


Thank you

-
They are left-aligned, but the delimiter glyph [ in this font has a margin. –  yo' Sep 2 '14 at 8:49
Adding a \! before the bmatrix almost annihilates this margin (~ 0.5pt of difference in alignment). –  Bernard Sep 2 '14 at 9:08
Thank you Bernard. It also works nicely. –  user124471 Sep 2 '14 at 9:26

This is a very dirty trick, but it works. It aligns the matrices' elements rather than the delimiters.

\documentclass[11pt,a4paper,oneside]{report}
\usepackage[pdftex]{graphicx}
\usepackage[T1]{fontenc}
\usepackage{fouriernc}
\usepackage{mathtools}
\usepackage{amsfonts,amsmath,amssymb,amsthm}
\usepackage[a4paper, hmargin={3.5cm,3cm}, vmargin={2.5cm,2.5cm}]{geometry} % margin
\usepackage{multicol}

\begin{document}
\begin{gather*}
\renewcommand\arraystretch{1.4}
\begin{bmatrix}
a_{1}&u_{2}&\frac{a_{1}}{d}u_{3}\\
a_{2}&u_{1}&\frac{a_{2}}{d}u_{3}\\
a_{3}&0&u_{4}\\
\end{bmatrix}\mathrel{\phantom{=1}}
\intertext{with}
\renewcommand\arraystretch{1.4}
\begin{vmatrix}
a_{1}&u_{2}&\frac{a_{1}}{d}u_{3}\\
a_{2}&u_{1}&\frac{a_{2}}{d}u_{3}\\
a_{3}&0&u_{4}
\end{vmatrix}=1
\end{gather*}
\end{document}

-
Dirty or not, but it surely does the job. Thank you! –  user124471 Sep 2 '14 at 8:56
@user124471 I just realized that the \mathclap construct is a non-sense and can be removed. It is much less dirty now :) –  yo' Sep 2 '14 at 8:58
Ok, I will remove it. Thanks again. –  user124471 Sep 2 '14 at 9:00