2-d graph

### 3.2.1 2-d graph

`plotfunc(f(x),x)` draws the graph of y=f(x) for x in the default interval, `plotfunc(f(x),x=a..b)` draws the graph of y=f(x) for a≤ x≤ b. `plotfunc` accepts an optional `xstep=...` argument to specify the discretisation step in x.
Input :

`plotfunc(x```^```2-2)`

or

`plotfunc(a```^```2-2,a=-1..2)`

Output :

`the graph of y=x```^```2-2`

Input :

`plotfunc(x```^```2-2,x,xstep=1)`

Output :

`a polygonal line which is a bad representation of y=x```^```2-2`

It is also possible to specify the number of points used for the representation of the function with `nstep=` instead of `xstep=`. For example, input :

`plotfunc(x```^```2-2,x=-2..3,nstep=30)`