Align doesn´t align equations at equal sign [closed]

Question

I´m trying to align multiple equations below each other using align. However the equations are aligned at the right end instead of centered and aligned at the equal sign.

My Latex code looks like this:

\begin{align}
\mathbf{i}_{t} = \sigma(\mathbf{W}_{xi}\mathbf{x}_{t} + 
\mathbf{W}_{hi}\mathbf{h}_{t-1} + \mathbf{W}_{ci}\circ\mathbf{c}_{t-1} + 
\mathbf{b}_{i})\\
\mathbf{f}_{t} = \sigma(\mathbf{W}_{xf}\mathbf{x}_{t} + 
\mathbf{W}_{hf}\mathbf{h}_{t-1} + \mathbf{W}_{cf}\circ\mathbf{c}_{t-1} + 
\mathbf{b}_{f})\\
\mathbf{c}_{t} = \mathbf{f}_{t}\circ\mathbf{c}_{t-1} + \mathbf{i}_{t}\circ 
tanh(\mathbf{W}_{xc}\mathbf{x}_{t} + \mathbf{W}_{hc}\mathbf{h}_{t-1} + 
\mathbf{b}_{c})
\end{align}

And the output generated looks like this:

However the equations should be aligned at the equal sign. I´ve already tried multiple approaches but I simply can´t get it to work.

Thank you for your help.

Answer 1

You should give & symbol, where you want to align:

\documentclass{book}
\usepackage{amsmath}
\begin{document}

\begin{align}
\mathbf{i}_{t} &= \sigma(\mathbf{W}_{xi}\mathbf{x}_{t} + 
\mathbf{W}_{hi}\mathbf{h}_{t-1} + \mathbf{W}_{ci}\circ\mathbf{c}_{t-1} + 
\mathbf{b}_{i})\\
\mathbf{f}_{t} &= \sigma(\mathbf{W}_{xf}\mathbf{x}_{t} + 
\mathbf{W}_{hf}\mathbf{h}_{t-1} + \mathbf{W}_{cf}\circ\mathbf{c}_{t-1} + 
\mathbf{b}_{f})\\
\mathbf{c}_{t} &= \mathbf{f}_{t}\circ\mathbf{c}_{t-1} + \mathbf{i}_{t}\circ 
\tanh(\mathbf{W}_{xc}\mathbf{x}_{t} + \mathbf{W}_{hc}\mathbf{h}_{t-1} + 
\mathbf{b}_{c})
\end{align}

\end{document}