Strange Dot Product definition

In summary, the dot product can be defined as (1/4)[Norm(A+B)^2-Norm(A-B)^2] and this formula connects to the common one, Dot(A,B)=Sum(ai*bi), through the polarization identities. The euclidean magnitude of a vector is used in the latter formula.
  • #1
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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  • #2
##|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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  • #3
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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  • #4
Sorry I'm late! I have read the replies some time ago...very useful! Thanks!
 
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What is the definition of a "Strange Dot Product"?

The strange dot product is a mathematical operation that takes two vectors and produces a scalar value. It differs from the traditional dot product in that it includes an additional term that involves the cross product of the two vectors.

Why is it called a "Strange Dot Product"?

The name "strange" comes from the fact that it deviates from the traditional definition of the dot product. The additional term involving the cross product makes it unique and "strange" compared to the standard dot product.

What are the applications of the Strange Dot Product?

The strange dot product has applications in physics, particularly in the study of electromagnetic fields and fluid dynamics. It is also used in computer graphics and computer vision for tasks such as object recognition and image processing.

How is the Strange Dot Product calculated?

The formula for calculating the strange dot product is: A • B = AxBx + AyBy + AzBz + (AxBy - AyBx) + (AxBz - AzBx) + (AyBz - AzBy). This includes the traditional dot product (A • B = AxBx + AyBy + AzBz) as well as the additional cross product terms.

What are the properties of the Strange Dot Product?

Some properties of the strange dot product include: distributivity, commutativity, and associativity. It also follows the Cauchy-Schwarz inequality and can be used to calculate the angle between two vectors. However, it is not always positive-definite like the traditional dot product.

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