Strange Dot Product definition

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SUMMARY

The discussion centers on the definition of the dot product, specifically the formula Dot(A,B)=(1/4)[Norm(A+B)^2-Norm(A-B)^2]. This definition is linked to the common dot product formula Dot(A,B)=Sum(ai*bi) through the use of the polarization identity. The connection is established by recognizing that the Norm() function refers to the Euclidean magnitude of a vector, which is essential for deriving the standard dot product formula. The conversation highlights the mathematical relationship between different representations of the dot product.

PREREQUISITES
  • Understanding of vector operations
  • Familiarity with Euclidean norms
  • Knowledge of polarization identities in mathematics
  • Basic algebraic manipulation skills
NEXT STEPS
  • Study the derivation of the polarization identity in linear algebra
  • Learn about Euclidean norms and their properties
  • Explore vector operations and their applications in physics
  • Investigate alternative definitions of the dot product in different mathematical contexts
USEFUL FOR

Students of mathematics, educators teaching linear algebra, and professionals in fields requiring vector analysis will benefit from this discussion.

TonyEsposito
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Hi i have seen in abook the dot product defined as follows:
Dot(A,B)=(1/4)[Norm(A+B)^2-Norm(A-B)^2]
how this definition connect with the common one: Dot(A,B)=Sum(ai*bi)
Thanks!
 
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##|A+B|^2-|A-B|^2=|A|^2+2A\cdot B+|B|^2-|A|^2+2A\cdot B-|B|^2=4A\cdot B##.
 
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TonyEsposito said:
Hi i have seen in abook the dot product defined as follows:
Dot(A,B)=(1/4)[Norm(A+B)^2-Norm(A-B)^2]
how this definition connect with the common one: Dot(A,B)=Sum(ai*bi)
Thanks!

You have written one of the "polarization identities".
You get the "Dot(A,B)=Sum(ai*bi)" formula if your Norm() is the euclidean magnitude of a vector.
 
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Sorry I'm late! I have read the replies some time ago...very useful! Thanks!
 
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