Wave Propagation in Linear Media | re-examined
Wave Propagation in Linear Media | re-examined
Wave Propagation in Linear Media | re-examined
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Chapter 8<br />
8 Application of the quadratu<strong>re</strong> rout<strong>in</strong>e<br />
Application of the quadratu<strong>re</strong><br />
rout<strong>in</strong>e<br />
Newton Verstehen Sie etwas von Elektrizitat, Richard?<br />
Inspektor Ich b<strong>in</strong> ke<strong>in</strong> Physiker.<br />
Newton Ich verstehe auch wenig davon. Ich stelle nur aufgrund von<br />
Naturbeobachtungen e<strong>in</strong>e Theorie daruber auf. Diese Theorie sch<strong>re</strong>ibe ich<br />
<strong>in</strong> der Sprache der Mathematik nieder und erhalte meh<strong>re</strong><strong>re</strong> Formeln. Dann<br />
kommen die Techniker. Sie kummern sich nur noch um die Formeln. Sie<br />
gehen mit der Elektrizitat um wie der Zuhalter mit der Dirne. Sie nutzen<br />
sie aus. Sie stellen Masch<strong>in</strong>en her, und brauchbar ist e<strong>in</strong>e Masch<strong>in</strong>e erst<br />
dann, wenn sie von der Erkenntnis unabhangig geworden ist, die zu ih<strong>re</strong>r<br />
Er ndung fuhrte. Friedrich Dur<strong>re</strong>nmatt, Die Physiker<br />
Hav<strong>in</strong>g a quadratu<strong>re</strong> rout<strong>in</strong>e at hand that is capable of deal<strong>in</strong>g with ir<strong>re</strong>gularly oscillat<strong>in</strong>g<br />
functions, we can now apply it to the wave <strong>in</strong>tegrals of the rst part of this work | as an<br />
example, we choose the tunnel<strong>in</strong>g particle. To this end, a little bit of <strong>re</strong>writ<strong>in</strong>g is necessary<br />
to permit an e cient computation. In this chapter, we shall develop a Mathematica package<br />
compris<strong>in</strong>g all functions necessary to compute the wave function <strong>in</strong>side and outside the tunnel<br />
as well as provid<strong>in</strong>g a simple user <strong>in</strong>terface. F<strong>in</strong>ally, we shall test the implementation both<br />
numerically and analytically.<br />
The<strong>re</strong> is a good <strong>re</strong>ason why weselect the tunnel e ect to demonstrate what the quadratu<strong>re</strong><br />
rout<strong>in</strong>e is capable of: from all physical models we discussed <strong>in</strong> the rst part, this is by far the<br />
most <strong>in</strong>tricate one. While we mighthave succeeded with standard algorithms <strong>in</strong> all other cases,<br />
this one <strong>re</strong>ally calls for our non-standard approach. But not only a<strong>re</strong> the <strong>in</strong>tegrals di cult to<br />
compute, the variety of functions also <strong>re</strong>sults <strong>in</strong> a complex structu<strong>re</strong> of the package. Hav<strong>in</strong>g<br />
understood the implementation of this example, one can easily deduce the others.<br />
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