2D parametric curve

### 7.14.1 2D parametric curve

To draw a parametric curve in ℝ2:

- plotparam takes two mandatory and one optional argument:
  - exprs, a list of two real expressions or one complex expression involving the parameter.
  - var, the parameter, optionally with a range var=a..b. If no range is given, the values of t- and t+ from the graphics configuration will be used (see Section 2.5.8).
  - Optionally, tstep=n, to set the discretization step.
- plotparam(exprs,var ⟨ ,tstep=n⟩) draws the parametric representation of the curve.

#### Examples

- Input:
  plotparam(cos(x)+i*sin(x),x)
  or:
  plotparam([cos(x),sin(x)],x)
  Output:
- Input:
  plotparam(sin(t)+i*cos(t),t=-4..1)
  or:
  plotparam(sin(x)+i*cos(x),x=-4..1)
  or (with t-=4,t+=1 in the graphic configuration):
  plotparam(sin(t)+i*cos(t))
  Output:
  Input:
  plotparam(sin(t)+i*cos(t),t=-4..1,tstep=0.5)
  or (with t-=4,t+=1 in the graphic configuration):
  plotparam(sin(t)+i*cos(t),t,tstep=0.5)
  Output: