https://latex.codecogs.com/eqneditor/editor.php

\\
d_b:=\text{cumulated branch length}
\\
k:=\text{number of spots of a branch}
\\
\vec{s_{i}} = i^{th}\text{spot of a branch}
\\
sin_b:=\text{sinuosity of branch}
\\
d_b=\sum_{i=1}^{k-1} \left | \vec{s_{i+1}} - \vec{s_{i}} \right|
\\
sin_b=\frac{d_b}{\left | \vec{s_k} - \vec{s_{1}} \right|}
