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Introduction to Vectors and Tensors Vol 2 (Bowen 246). - Index of

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332 Chap. 9 • EUCLIDEAN MANIFOLDS<br />

Section 46. Anholonomic <strong>and</strong> Physical Components <strong>of</strong> <strong>Tensors</strong><br />

In many applications, the components <strong>of</strong> interest are not always the components with<br />

g<br />

j . For definiteness let us call the components <strong>of</strong> a<br />

respect <strong>to</strong> the natural basis fields { } i<br />

g <strong>and</strong> { }<br />

tensor field A ∈T ∞<br />

q<br />

( U ) is defined by (45.20) the holonomic components <strong>of</strong> A . In this section, we<br />

shall consider briefly the concept <strong>of</strong> the anholonomic components <strong>of</strong> A ; i.e., the components <strong>of</strong><br />

A taken with respect <strong>to</strong> an anholonomic basis <strong>of</strong> vec<strong>to</strong>r fields. The concept <strong>of</strong> the physical<br />

components <strong>of</strong> a tensor field is a special case <strong>and</strong> will also be discussed.<br />

Let<br />

1<br />

e a<br />

denote a set <strong>of</strong> N vec<strong>to</strong>rs fields on U<br />

1<br />

, which are<br />

linearly independent, i.e., at each x ∈U 1<br />

, { e a } is a basis <strong>of</strong> V . If A is a tensor field in T ∞ q<br />

( U )<br />

where U ∩ ≠∅<br />

1<br />

U , then by the same type <strong>of</strong> argument as used in Section 45, we can write<br />

U be an open set in E <strong>and</strong> let { }<br />

a<br />

a<br />

1<br />

q<br />

A aa 1 2 ... a<br />

e e<br />

q<br />

A = ⊗⋅⋅⋅⊗<br />

(46.1)<br />

or, for example,<br />

b1<br />

... b q<br />

eb<br />

e<br />

1<br />

bq<br />

A = A ⊗⋅⋅⋅⊗<br />

(46.2)<br />

where { a<br />

}<br />

e is the reciprocal basis field <strong>to</strong> { }<br />

e defined by<br />

a<br />

a<br />

a<br />

e ( x) ⋅ e ( x ) = δ<br />

(46.3)<br />

b<br />

b<br />

for all x ∈U 1<br />

. Equations (46.1) <strong>and</strong> (46.2) hold on U ∩U 1<br />

, <strong>and</strong> the component fields as defined by<br />

A<br />

...<br />

= A ( e ,..., e )<br />

(46.4)<br />

aa 1 2 aq<br />

a1<br />

aq<br />

<strong>and</strong><br />

b1 ... bq<br />

b b<br />

1<br />

q<br />

A = A ( e ,..., e )<br />

(46.5)

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