Example 8.  Determine the conic that passes through the five points  [Graphics:Images/ConicFitMod_gr_98.gif].  

Solution 8.

The points are entered into Mathematica with the command:

 

[Graphics:../Images/ConicFitMod_gr_99.gif]

Then a row vector corresponding to equation (11) is defined:

 

[Graphics:../Images/ConicFitMod_gr_100.gif]

The matrix A for the linear system in (12) and the determinant is now created.  The vector R is stored in the first row by issuing the command  A = {R}.  Then the remaining five rows of A are generated with the loop command:

[Graphics:../Images/ConicFitMod_gr_101.gif]


[Graphics:../Images/ConicFitMod_gr_102.gif]

For the given five points, the homogeneous system AC = 0 is:

 

[Graphics:../Images/ConicFitMod_gr_103.gif]

 

The determinant of this matrix is computed by typing:

[Graphics:../Images/ConicFitMod_gr_104.gif]


[Graphics:../Images/ConicFitMod_gr_105.gif]

This quantity is multiplied by  [Graphics:../Images/ConicFitMod_gr_106.gif]to get the desired equation:

[Graphics:../Images/ConicFitMod_gr_107.gif]


[Graphics:../Images/ConicFitMod_gr_108.gif]

The conic is the parabola shown in Figure 8.  It is plotted using the commands:

[Graphics:../Images/ConicFitMod_gr_109.gif]


[Graphics:../Images/ConicFitMod_gr_110.gif]

[Graphics:../Images/ConicFitMod_gr_111.gif]

[Graphics:../Images/ConicFitMod_gr_112.gif]

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

(c) John H. Mathews 2004