How to align several equations in latex

[tabasco]

I'm trying to align several equations in latex. One of them is too long to fit in one line however, and I want to align that one in a way, where corresponding terms (in parentheses) are aligned - in addition to the alignment of the equal signs. This is what I want:

####$#y1 = a*x + b*z y2 = K*y1 = a*(x1 + x2) + b*(z1 + z2) y3 = K*y2 = a*(x1 + x2) + b*(c*(z1 + z2)$###########################+ d*(z1 – z2))



The ### are placeholders so I could get the alignment right in this post.


Is there any way of doing this properly? Without \quad and the likes... ?
By inserting additional alignment tags only in the last equation?



- T

 

[chroot]

Is there any way of doing this properly?

Like this?

$$\begin{array}{rrrcll} &&y1&=&a*x + b*z&\\ y2&=&K*y1&=&a*(x1 + x2)&+\ b*(z1 + z2)\\ y3&=&K*y2&=&a*(x1 + x2)&+\ b*(c*(z1 + z2)\\ &&&&&+\ d*(z1 – z2)) \end{array}$$

It doesn't look like it's too long to go on one line, but whatever.

- Warren

 

[tabasco]

Chroot, thanks for the quick reply
but it doesn't quite solve my problem: The variables I put down in the post are really more complex terms. So the first line is already way longer than what it looks like in the post and am using the twocolumn-mode for an article.

So there are two points I want aligned: First, for all three equations, the row of three equal-signs, just how it is in your reply. That's simple...

Second, the "+" in line three with the "c" in line 4. The hard part is doing that without ripping the above lines apart. There is no corresponding alignment point in the first two lines.
Since the first line is really longer than what I put down here I don't know where to put an extra "&"...

Phew, I hope you understand that explanation...

- T

 

[robphy]

$$\begin{align*} y1&=a*x + b*z\\ y2=K*y1&=a*(x1 + x2)+\ b*(z1 + z2)\\ y3=K*y2&=a*(x1 + x2)+\ b*(c*(z1 + z2)\\ &&\hspace*{-26ex}+\ d*(z1 – z2)) \end{align*}$$

Is using \hspace cheating? (Note the extra & in the last line.)

 

[tabasco]

I guess I could do it like that... but yes, I think that would be cheating. The hspace needed is trial and error, and when I change the fontsize I'd have to change the spacing manually, right.

Maybe there's a way of inserting "invisible" text? If I could insert everything from the upper line up until the point I want aligned without displaying it, that would work... Any ideas?

- T

 

[robphy]

By specifying the dimensions in units of ex, I would think that the spacing would scale reasonably well.

$$\begin{align*} y1&=a*x + b*z\\ y2=K*y1&=a*(x1 + x2)+\ b*(z1 + z2)\\ y3=K*y2&=a*(x1 + x2)+\ b*(c*(z1 + z2)\\ &\hphantom{=a*(x1 + x2)+\ b*(}+\ d*(z1 – z2)) \end{align*}$$

You can use the phantom (\[hv]phantom) tags.

 

[nbo10]

Try using a matrix.

JMD

 

[robphy]

$$\begin{align*} y1&=a*x + b*z\\ y2=K*y1&=a*(x1 + x2)+\ b*(z1 + z2)\\ y3=K*y2&=a*(x1 + x2)+ \begin{array}[t]{ll} b*(&\!\!\! c*(z1 + z2)\\ &\!\!\! +\ d*(z1 – z2)) \end{array} \end{align*}$$

This is a little cleaner... but it messes up the algebraic meaning.

 

[Tom McCurdy]

I am actually working on useing latex on my own forum ... hopefully it will work well

 

[Tom McCurdy]

If you want to see my progress go to www.quantumninja.com/QuantumGravity