I have the fourth edition of Dirac's Principles of QM. I have a question concerning the equation in the middle of page 102 (between eqns 64 and 65 in section 25.)(adsbygoogle = window.adsbygoogle || []).push({});

[tex]\lim_{\delta x \rightarrow 0}(De^{i\gamma} - 1)/\delta x = \lim_{\delta x \rightarrow 0}(D - 1 + i \gamma)/\delta x[/tex]

If you make the substitution [itex]e^{i\gamma} \simeq 1 + i \gamma[/itex] then it seems to me you should get

[tex]\lim_{\delta x \rightarrow 0}(De^{i\gamma} - 1)/\delta x = \lim_{\delta x \rightarrow 0}(D - 1 + i \gamma D)/\delta x[/tex]

What am I missing?

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# Homework Help: Question from Dirac's Principles of QM

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