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Thanks, that's perfect.

Hi,

I am making a matrix with a red line through the first column and row. I have code that works for making this matrix, but when I try to put it into the alignat environment I get an error. Here is the (working) code that draws the matrix:


\documentclass[12pt]{article}
\usepackage{amsmath ...

Hi,
The default spacing of the array environment puts fractions in the same column too close together (vertically) for my liking. This is my code:

\documentclass[12pt]{article}
\begin{document}
\[
\left(\begin{array}{ccc|c}
1&2&-1&-1\\
0&1&\frac{3}{2}&\frac{9}{2}\\
0&0&\frac{11}{2}&\frac{55}{2 ...

Thanks localghost, alignat works perfectly for this. I had tried using it before but with no success. Substack was the key ingredient I was missing. This is what I ended up with:
\documentclass[12pt]{article}
\usepackage[T1]{fontenc}
\usepackage[utf8]{inputenc}
\usepackage{mathtools}
\begin ...

I want to align these large blocks of stuff and I was wondering what the best way to do it is. I essentially want four columns: the first will be a multi-line description of the operation, the second will be a matrix, the third will be another multi-line description, and the fourth will be another ...

Thanks Juanjo for explaining what all those ampersands are for. I couldn't find a good explanation but that makes me a lot more comfortable using it. Also thanks for catching that superfluous +.

Can you explain why "+{}" produces the correct spacing while "{}+{}" does not? It seems to me that they ...

Thanks Stefan! That is exactly what I wanted. I think there were some typos in your code though.. LaTeX didn't give me errors when I changed it to
\begin{alignat*}{4}
5x_1 &+ 3x_2 &+ x_3 &= 0\\
x_1 &+ &- 4x_3 &= 0\\
&- 9x_2 &+ 2x_3 &= 0
\end{alignat*}

-Tony

This is almost what I am looking for but there is too much space between the elements of the array. I want mine to read just like an equation (like the rest of my equations that aren't arrays) so that my paper is consistent. I tried this:

\begin{align*}
5x_1&+3x_2&+x_3&=0\\
x_1&+{}&-4x_3&=0 ...

That's really great gmedina, and I know i'm being nit-picky at this point, but is there a way that the highlighted cells can be highlighted by a triangle rather than the stair-step shape generated by this code. It may only make sense physically to do this with matrices that only have single ...

Thanks, Stefan, that did the trick

It also shifted the title of the example but I modified the environment by adding \flushleft before the title of the example to fix that.

-Tony