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The following tables display the error in the first 10 recovered eigenvalues. Listed are the eigenvalues numerically recovered from q ( t ) and those recovered from its transformed counterpart, ρ ( x ) . As expected, those recovered from q ( t ) are accurate to over ten decimal digits. This is a consequence of the accuracy of the spectral method with sufficient Chebyshev points. The error in the eigenvalues recovered from ρ ( x ) reflects the numerical error in our ODE solver. However, the error is tolerable. In addition, we see that the error in the transformation of the q ( t ) defined by μ 1 = 9 is less than for the other choices of μ 1 listed in the tables.

μ 1 = 1
True λ Recovered λ ( q ( t ) ) Error from q ( t ) Recovered λ ( ρ ( x ) ) Error from ρ ( x )
1.0000000 1.0000000 2.5930147e-011 1.0054709 5.4708902e-003
39.4784176 39.4784176 1.0608403e-011 39.5200555 4.1637860e-002
88.8264396 88.8264396 1.5930368e-011 88.9392066 1.1276694e-001
157.9136704 157.9136704 1.4694024e-011 157.9977790 8.4108586e-002
246.7401100 246.7401100 2.2168933e-012 247.2588167 5.1870663e-001
355.3057584 355.3057584 1.6484591e-011 354.0659603 1.2397981e+000
483.6106157 483.6106157 8.5265128e-013 486.5704124 2.9597967e+000
631.6546817 631.6546817 5.1159077e-012 620.2338813 1.1420800e+001
799.4379565 799.4379565 9.7770680e-012 816.7159848 1.7278028e+001
986.9604401 986.9604401 2.6602720e-011 973.9089831 1.3051457e+001
μ 1 = 9
True λ Recovered λ ( q ( t ) ) Error from q ( t ) Recovered λ ( ρ ( x ) ) Error from ρ ( x )
9.0000000 9.0000000 2.3881341e-011 9.0000369 3.6905319e-005
39.4784176 39.4784176 2.0996538e-011 39.4791540 7.3639246e-004
88.8264396 88.8264396 2.1927349e-011 88.8280954 1.6558273e-003
157.9136704 157.9136704 1.7990942e-011 157.9166007 2.9303014e-003
246.7401100 246.7401100 4.2064130e-012 246.7446791 4.5690754e-003
355.3057584 355.3057584 2.1827873e-011 355.3123306 6.5721222e-003
483.6106157 483.6106157 2.1032065e-011 483.6195551 8.9394021e-003
631.6546817 631.6546817 3.3082870e-011 631.6663524 1.1670772e-002
799.4379565 799.4379565 1.3528734e-011 799.4527229 1.4766388e-002
986.9604401 986.9604401 3.4106051e-013 986.9786662 1.8226098e-002
μ 1 = 15
True λ Recovered λ ( q ( t ) ) Error from q ( t ) Recovered λ ( ρ ( x ) ) Error from ρ ( x )
15.0000000 15.0000000 8.2795992e-012 14.9930764 6.9236370e-003
39.4784176 39.4784176 1.5845103e-012 39.4741052 4.3124162e-003
88.8264396 88.8264396 6.0538241e-012 88.8165421 9.8974784e-003
157.9136704 157.9136704 8.0433438e-012 157.8982531 1.5417339e-002
246.7401100 246.7401100 2.8421709e-014 246.7173201 2.2789901e-002
355.3057584 355.3057584 1.1766588e-011 355.2739142 3.1844196e-002
483.6106157 483.6106157 2.8762770e-011 483.5680542 4.2561441e-002
631.6546817 631.6546817 8.7538865e-012 631.5997459 5.4935770e-002
799.4379565 799.4379565 3.4106051e-011 799.3689927 6.8963814e-002
986.9604401 986.9604401 2.3192115e-011 986.8757937 8.4646413e-002

For the majority of our research, the focus was on the potential function [link] from chapter 6 of [link] . In the next section, some results will be discussed for other q ( t ) or ρ ( x ) in closed form.

Corresponding q ( t ) And ρ ( x ) Functions in closed form

The potential function q ( t ) given by [link] from chapter 6 of [link] , after taking the second derivative of the Wronskian, becomes

q ( t ) = - 2 - π 3 cos ( π t ) f ( t ) - π 2 sin ( π t ) f ' ( t ) + π μ 1 cos ( π t ) f ( t ) + μ 1 sin ( π t ) f ' ( t ) π cos ( π t ) f ( t ) - sin ( π t ) f ' ( t ) = - - π 2 sin ( π t ) f ( t ) + μ 1 sin ( π t ) f ( t ) 2 - π cos ( π t ) f ( t ) - sin ( π t ) f ' ( t ) 2

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Source:  OpenStax, The art of the pfug. OpenStax CNX. Jun 05, 2013 Download for free at http://cnx.org/content/col10523/1.34
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