Equivalence of two complex expressions

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Discussion Overview

The discussion revolves around the equivalence of two complex expressions, specifically focusing on the principal value of the product of two complex numbers raised to an exponent versus the product of the two complex numbers each raised to the same exponent. The scope includes conceptual clarification and mathematical reasoning related to complex numbers.

Discussion Character

  • Conceptual clarification, Mathematical reasoning, Debate/contested

Main Points Raised

  • One participant questions the equivalence of ## e^{-i \frac {3\pi}{8}} ## and ## e^{i \frac {5\pi}{8}} ##.
  • Another participant asserts that the two expressions are not equivalent, explaining that they correspond to points on a unit circle that are diametrically opposite.
  • A third participant provides a mathematical transformation, showing that ## e^{-i \frac{3 \pi}{8}} ## can be expressed as ## e^{i \frac{13 \pi}{8}} ##, which is not equal to ## e^{i \frac{5 \pi}{8}} ##.
  • A later reply acknowledges a mistake in interpreting the denominator in the original expression, leading to confusion about the equivalence.

Areas of Agreement / Disagreement

Participants generally disagree on the equivalence of the two complex expressions, with multiple viewpoints presented regarding their relationship on the unit circle.

Contextual Notes

The discussion highlights potential misunderstandings related to the interpretation of complex exponentials and their geometric representation on the unit circle.

TheCanadian
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I found the above while going through my textbook, where the textbook was trying to explain that the principal value of the product of two complex numbers raised to an exponent is not necessarily equivalent to the product of the two complex number each raised to the same exponent first.

Based on the above, what exactly is the difference in the two expressions? Is not ## e^{-i \frac {3\pi}{8}} ## equivalent to ## e^{i \frac {5\pi}{8}} ##?
 
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TheCanadian said:
Is not ## e^{-i \frac {3\pi}{8}} ## equivalent to ## e^{i \frac {5\pi}{8}} ##?
No, they're not equivalent. They refer to points on a unit circle that diametrically opposite one another.
 
Mark44 said:
No, they're not equivalent. They refer to points on a unit circle that diametrically opposite one another.

Yikes, it's been a long night. For some reason I mistook the 8 in the denominator of the fraction as a 4. Thank you.
 

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