I How Are Base Vectors Defined in Covariance and Contravariance?

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Base vectors in covariance and contravariance are defined through the gradient of coordinate functions, where covariant base vectors are normal to these functions and tangent vectors represent the coordinate lines. The confusion arises from understanding how these definitions apply in practice, particularly in the context of the relationships between the base vectors and their magnitudes. The covariant base vector, expressed as e(1) = ∇u, is derived from the normal vector definition, while the tangent vectors are defined by their orientation along the coordinate lines. Clarification is sought on the mathematical relationships, such as the dot products and their implications for orthogonality and magnitude. Understanding these definitions and relationships is crucial for grasping the concepts of covariance and contravariance in vector spaces.
Somali_Physicist
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I'm confused at how the base vectors are found for both.

e(1) = ∂r/∂u
e(1)= ∇u
where r = xi + yj+zk
x = x(u,v,w)
y=y""
z=z""

cant understand why.
 
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Exactly what is it that confuses you?
 
Orodruin said:
Exactly what is it that confuses you?
How the covariant and contravariant base vectors are found.
For instance the covariant base vectors is found through:
e1 = ∇u , why is this?
 
It is a definition.

You choose those base vectors to be normal vectors to the coordinate functions. The normal vector of a function is given by its gradient.

The other set of base vectors is chosen to be the tangent vectors of the coordinate lines.
 
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Orodruin said:
It is a definition.

You choose those base vectors to be normal vectors to the coordinate functions. The normal vector of a function is given by its gradient.

The other set of base vectors is chosen to be the tangent vectors of the coordinate lines.
not to sound slow but just to clarify.

e1 ⋅ (equivalent coordinate function base) = 0
e1⋅(equivalent coordinate function base) = 0
e1 ⋅ (equivalent coordinate function base) = e1⋅(equivalent coordinate function base)
e1 ⋅(1/e1) = 1
∂u/∂x ⋅ ∂u/∂x = ε^2 ( magnitude)
=ε^2cosθ , if orthogonal , = 1
Is that the rational they took to get use the vectors?
 
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