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

##### 7.67.1 Sergei Zuyev

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 )



##### 7.67.2 Ha Quang Le (11.2.98)

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]