docs/2016-11-03-trajectory.md

@@ -68,7 +68,7 @@ rA="31.29"	rB="23.87"	eO="-175.41" eC="54"/>
   "ellipseOrientation" is the angle between the  major axis and the X-axis (zero for circle). 
    A color can also be provided, for example for displaying change in velocity. 
    The colours are in the range `[0=red, 255=green]` and define the proportion between 
-   the desired speed ($$v_0$$) and the instantaneous velocity.
+   the desired speed ($`v_0`$) and the instantaneous velocity.