#### 7.67 Bug in geometry[ellipse] in Maple V.4 (9.2.98)

Here is geometry-bug.mws ﬁle consisting just of a few lines and visualizing the following bug
in `geometry[ellipse]`

procedure: ellipse is computed incorrectly if in its deﬁnition one uses
ﬂoats.

Maple Release 4 Version 4.00f of 2 Dec. 1996

`geometry[ellipse]`

bug report

> restart:
> with(geometry):

Deﬁne two ellipses given by the same equation but written in integers and ﬂoats:

> _EnvHorizontalName := 'x': _EnvVerticalName := 'y':
> ellipse(e1,x^2/2+y^2=1 ):
> ellipse(e2,x^2/2+y^2=1.0):

Now observe the result (the erroneous one is in red):

> draw({e1(color=green),e2(color=red)},scaling=CONSTRAINED,axes=NORMAL);

Let’s verify that it is NOT a bug of draw:

> ?geometry[ellipse];
> coordinates(center(e1));
[0, 0]
> coordinates(center(e2));
[-1.000000000, -1.000000000]

The help topic on geometry[ellipse] also contains misprints in the command syntax: " ] " is
lost:

ellipse(p, ['directrix'=dir,'focus'=fou, 'eccentricity'=ecc, n )
ellipse(p, ['foci'=foi,'MajorAxis'=lma,n )
ellipse(p, ['foci'=foi,'MinorAxis'=lmi,n )
ellipse(p, ['foci'=foi,'distance'=dis,n )
ellipse(p, ['MajorAxis'=ep1, 'MinorAxis'=ep2,n )

should deﬁnitely be

ellipse(p, ['directrix'=dir,'focus'=fou, 'eccentricity'=ecc], n )
ellipse(p, ['foci'=foi,'MajorAxis'=lma],n )
ellipse(p, ['foci'=foi,'MinorAxis'=lmi],n )
ellipse(p, ['foci'=foi,'distance'=dis],n )
ellipse(p, ['MajorAxis'=ep1, 'MinorAxis'=ep2],n )

The bug is ﬁxed in release 5:

> with(geometry):
Define two ellipses given by the same equation but written in integers and floats:
\begin{MAPLEinline}
> _EnvHorizontalName := 'x': _EnvVerticalName := 'y':
> ellipse(e1,x^2/2+y^2=1 ):
> ellipse(e2,x^2/2+y^2=1.0):
> coordinates(center(e1));
[0, 0]
> coordinates(center(e2));
[0, 0]