Example 3.  Use cubic spline quadrature to compute a numerical approximation to the integral  [Graphics:Images/SplineQuadMod_gr_110.gif].  
Use the tolerances [Graphics:Images/SplineQuadMod_gr_111.gif].  Compare with Mathematica's "numerical value" of the integral.

Solution 3.

[Graphics:../Images/SplineQuadMod_gr_112.gif]
[Graphics:../Images/SplineQuadMod_gr_113.gif]

3 (a). Plot the function over the interval  [0, 2].

[Graphics:../Images/SplineQuadMod_gr_114.gif]

[Graphics:../Images/SplineQuadMod_gr_115.gif]

[Graphics:../Images/SplineQuadMod_gr_116.gif]

3 (b). Construct the cubic spline for 11 nodes and use it for quadrature.

[Graphics:../Images/SplineQuadMod_gr_117.gif]

[Graphics:../Images/SplineQuadMod_gr_118.gif]
[Graphics:../Images/SplineQuadMod_gr_119.gif]

3 (c). Construct the cubic spline for 21 nodes and use it for quadrature.

[Graphics:../Images/SplineQuadMod_gr_120.gif]

[Graphics:../Images/SplineQuadMod_gr_121.gif]
[Graphics:../Images/SplineQuadMod_gr_122.gif]


3 (d). Construct the cubic spline for 41 nodes and use it for quadrature.

[Graphics:../Images/SplineQuadMod_gr_123.gif]

[Graphics:../Images/SplineQuadMod_gr_124.gif]
[Graphics:../Images/SplineQuadMod_gr_125.gif]

3 (e). Construct the cubic spline for 41 nodes and use it for quadrature.

[Graphics:../Images/SplineQuadMod_gr_126.gif]
[Graphics:../Images/SplineQuadMod_gr_127.gif]
[Graphics:../Images/SplineQuadMod_gr_128.gif]

3 (f). Compare the results from parts b-d.

[Graphics:../Images/SplineQuadMod_gr_129.gif]

m sample points

[Graphics:../Images/SplineQuadMod_gr_130.gif]

11

[Graphics:../Images/SplineQuadMod_gr_131.gif]

21

[Graphics:../Images/SplineQuadMod_gr_132.gif]

41

[Graphics:../Images/SplineQuadMod_gr_133.gif]

81

[Graphics:../Images/SplineQuadMod_gr_134.gif]

 

3 (g). Use Mathematica to find the numerical solution to the integral.

[Graphics:../Images/SplineQuadMod_gr_135.gif]


[Graphics:../Images/SplineQuadMod_gr_136.gif]

3 (h). How close did our last numerical approximation using Romberg integration come to Mathematica's "numerical value" of the integral.

[Graphics:../Images/SplineQuadMod_gr_137.gif]


[Graphics:../Images/SplineQuadMod_gr_138.gif]
[Graphics:../Images/SplineQuadMod_gr_139.gif]


[Graphics:../Images/SplineQuadMod_gr_140.gif]

[Graphics:../Images/SplineQuadMod_gr_141.gif]

[Graphics:../Images/SplineQuadMod_gr_142.gif]
[Graphics:../Images/SplineQuadMod_gr_143.gif]
[Graphics:../Images/SplineQuadMod_gr_144.gif]
[Graphics:../Images/SplineQuadMod_gr_145.gif]

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

(c) John H. Mathews 2004