### 2.3 Curves

To draw a plane curve: cartesian, polar, parametric.

• Shortcuts: Parametric curve: Ctrl+P, Polar curve: Ctrl+O, Cartesian curve: Ctrl+R.
• We must give a name.
• Then:
• For a cartesian curve $y=f\left(x\right)$, give the expression of f(x).
• For a polar curve $r=f\left(t\right)$, give the expression of f(t).
• For a parametric curve $\left(x\left(t\right),y\left(t\right)\right)$, give the expression of the function $f\left(t\right)=x\left(t\right)+i*y\left(t\right)$.
• We can set two curve’s parameters:
• Division(s): It’s a positive integer or zero that shows how many times TeXgraph can cut into two pieces (dichotomy) the interval between two consecutives values of t (5 by default). This raises the number of points in the neighbourhood of brutal variations.
• Discontinuité: 0 or 1, if it’s 1 and the distance between two consecutive points is above a certain level, then a discontinuity is inserted in the points list.
• The interval for the $t$ parameter (global variables tMin and tMax), is also the interval for the $x$ variable of the cartesian curves. That interval and the number of points (variable NbPoints) can be set using the Attributes button.
• Corresponding graphical commands Cartesienne(f(x)), Polaire(r(t)) and for the parametric curves : Courbe (to be used in a User-defined type element).