Latex AMS align / Align multiple "=", too much space

Question

I'd like to align some equations in Latex using the AMS packages. Each equation has two equal signs that need to be aligned. So something in the line of

A = B = C D = E = F 

I've tried using the align-environment like this

\begin{align} A &= B &= C \\ D &= E &= F \end{align} 

This works in principle (it aligns), however it adds ridiculously large spaces before the second equal sign in each line. But I just want the line to runs as if there was no additional alignment tab. Only when I replace for example "B" by "BBB" I want the equal sign before "F" to shift to right the exact amount of space.

Could anyone help me out on that one? It's kind of driving me crazy since I don't get the idea of that strange behavior and I just can't find any solution. Maybe alignat could help, but I don't really get how that environment works or in how it differs from normal align.

Cheers, Oliver

Answer 1

This should work:

\begin{alignat}{2}   A &= B & &=  C \\   D &= E & &=  F \end{alignat} 

From ams guide:

A variant environment alignat allows the horizontal space between equations to be explicitly specified. This environment takes one argument, the number of “equation columns”: count the maximum number of &s in any row, add 1 and divide by 2.

Its not exactly intended for what you are trying to do, but since align insists on adding space... The idea behind align is:

l&=r   &   l&=r \\ l&=r   &   l&=r 

One '&' per function, and a '&' between functions.

I would hope there is a better solution though.

Answer 2

(6½ to 8 years later)

What about using array with a custom separator?

\begin{array}{r@{\ }c@{\ }l} A &= B &= C \\ D &= E &= F \end{array}