>\(\displaystyle x = \frac {da} {dz}, y = \frac {db} {dz}, \displaystyle \frac {d \gamma} {dz} \approx \frac {e E_z} {mc ^ 2 },\)</span> then:</p>
<div class="math notranslate nohighlight">
\[\begin{split}\displaystyle
\left \{\begin{matrix}
\displaystyle \frac {dx} {dz} = - \frac {1} {\beta ^ 2 \gamma} \gamma 'a' - \frac {1} {2 \beta ^ 2 \gamma} \gamma'a - ka + \frac {2P} {(a + b)} + \frac {\epsilon_x ^ 2} {a ^ 3} \\
 \displaystyle \frac {da} {dz} = x \\
 \displaystyle \frac {dy} {dz} = - \frac {1} {\bet