Align Multiple Points: A LaTeX Problem

[ATY]

So, I got the following problem: I want to write my equation the way you can see it in the picture:

I am actually running this:

\ begin{align}
\begin{split}
...
\ end{split}
\ end{align}

My problem is, that I can not set multiple align points. I need one point to attach the first 4 lines to the left side (because due to split they would otherwise go to the ride side), but the lines 5-8 look like they got aligned to the "+" from the first line.
How do I do this ? I hope that somebody can answer my question.

 

[DrClaude]

You should be able to achieve this using alignat in amsmath.

http://tex.stackexchange.com/questions/49014/aligning-equations-with-text-with-alignat

 

[ATY]

ok, I tried it, but I got the following problem:
1. if I add a "&" at the beginning of every column to align the first 4 columns to the left side and additionally add an "&" before the "+" in the first column the program divides(?), because it thinks that I want to create a table.

2. if I do not use the "&" before at the beginning of the first 4 columns, I manage to align the lines 5-8 properly, but the first columns are suddenly alligned to the right side of my paper.

 

[DrClaude]

Sorry, that was a bad idea.

Thinking about it some more, try using fantom:

\begin{align*}
& + \frac{(\Delta t^4)}{6} [ (\frac{b}{8} + \frac{c}{8} + d)  \\
& \hphantom{{} + \frac{(\Delta t^4)}{6} [} (\frac{3c}{8} + \frac{3d}{4})
\end{align*}

$$
\begin{align*}

& + \frac{(\Delta t^4)}{6} [ (\frac{b}{8} + \frac{c}{8} + d) \\

& \hphantom{{} + \frac{(\Delta t^4)}{6} [} (\frac{3c}{8} + \frac{3d}{4})

\end{align*}
$$

 

[ATY]

this works fantastically :D
Thank you so much :)

 

[wle]

You can also use the IEEEeqnarray environment for this sort of thing (install the IEEEtrantools package and load with \usepackage[retainorgcmds]{IEEEtrantools}). There's a nice explanation at http://moser-isi.ethz.ch/docs/typeset_equations.pdf.

\begin{IEEEeqnarray*}{rCll}
  y^{n + 1} &=& \IEEEeqnarraymulticol{2}{l}{
    y^{n} + \Delta t \bigl[ (a + b + c + d) (f)_{t = t^{n}} \bigr]} \\
  && \IEEEeqnarraymulticol{2}{l}{+\> \dotsb} \\
  && +\> \frac{(\Delta t)^{4}}{6} \Biggl[ &
    \biggl( \frac{b}{8} + \frac{c}{8} + d \biggr)
    \biggl( \frac{\partial^{3} f}{\partial t^{3}}
      + 3 f \frac{\partial^{3} f}{\partial t^{2} \partial y}
      + 3 f^{2} \frac{\partial^{3} f}{\partial t \partial y^{2}}
      + f^{3} \frac{\partial^{3} f}{\partial y^{3}} \biggr)_{t = t^{n}} \\
    &&& +\> \biggl( \frac{3c}{8} + \frac{3d}{4} \biggr)
    \biggl( \frac{\partial^{2} f}{\partial t^{2}}
      + 2 f \frac{\partial^{2} f}{\partial t \partial y}
      + f^{2} \frac{\partial^{2} f}{\partial y^{2}} \biggr)_{t = t^{n}}
    \biggl( \frac{\partial f}{\partial y} \biggr)_{t = t^{n}} \\
    &&& +\> \dotsb \\
    &&& +\> \biggl( \frac{3c}{4} + 3d \biggr)
    \biggl( \frac{\partial f}{\partial t}
      + f \frac{\partial f}{\partial y} \biggr)_{t = t^{n}}
    \biggl( \frac{\partial^{2} f}{\partial t \partial y} \biggr)_{t = t^{n}}
  \Biggr] \\
  && \IEEEeqnarraymulticol{2}{l}{+\> \dotsb} \\
  && \IEEEeqnarraymulticol{2}{l}{
    +\> \mathcal{O} \bigl( (\Delta t)^{6} f^{(5)} \bigr) \,.} \IEEEyesnumber
\end{IEEEeqnarray*}

Produces this: