2D parametric curve

### 3.11.1 2D parametric curve

`plotparam([f(t),g(t)],t)` or `plotparam(f(t)+i*g(t),t)` (resp `plotparam(f(t)+i*g(t),t=t1..t2)`) draws the parametric representation of the curve defined by x=f(t),y=g(t) with the default range of values of t (resp for t1 ≤ t≤ t2).
The default range of values is taken as specified in the graphic configuration (`t-` and `t+`, cf. ??). `plotparam` accepts an optional argument to specify the discretisation step for t with `tstep=`.
Input :

`plotparam(cos(x)+i*sin(x),x)`

or :

`plotparam([cos(x),sin(x)],x)`

Output :

`The unit circle`

If in the graphic configuration `t` goes from -4 to 1, input :

`plotparam(sin(t)+i*cos(t))`

or :

`plotparam(sin(t)+i*cos(t),t=-4..1)`

or :

`plotparam(sin(x)+i*cos(x),x=-4..1)`

Output :

`the arc (sin(-4)+i*cos(-4),sin(1)+i*cos(1)) of the unit circle`

If in the graphic configuration `t` goes from -4 to 1, input :

`plotparam(sin(t)+i*cos(t),t,tstep=0.5)`

Or :

`plotparam(sin(t)+i*cos(t),t=-4..1,tstep=0.5)`

Output :

`A polygon approching the arc (sin(-4)+i*cos(-4),sin(1)+i*cos(1)) of the unit circle`