This is a list of some vector calculus formulae for working with common curvilinear coordinate systems .
This article uses the standard notation ISO 80000-2 , which supersedes ISO 31-11 , for spherical coordinates (other sources may reverse the definitions of θ and φ ):
The polar angle is denoted by θ ∈ [ 0 , π ] : it is the angle between the z -axis and the radial vector connecting the origin to the point in question.
The azimuthal angle is denoted by φ ∈ [ 0 , 2 π ] : it is the angle between the x -axis and the projection of the radial vector onto the xy -plane.
The function atan2 (y , x ) can be used instead of the mathematical function arctan (y /x ) owing to its domain and image . The classical arctan function has an image of (−π/2, +π/2) , whereas atan2 is defined to have an image of (−π, π] .
Conversion between Cartesian, cylindrical, and spherical coordinates[ 1]
From
Cartesian
Cylindrical
Spherical
To
Cartesian
x = x y = y z = z
x = ρ cos φ y = ρ sin φ z = z
x = r sin θ cos φ y = r sin θ sin φ z = r cos θ
Cylindrical
ρ = x 2 + y 2 φ = arctan ( y x ) z = z
ρ = ρ φ = φ z = z
ρ = r sin θ φ = φ z = r cos θ
Spherical
r = x 2 + y 2 + z 2 θ = arccos ( z x 2 + y 2 + z 2 ) φ = arctan ( y x )
r = ρ 2 + z 2 θ = arctan ( ρ z ) φ = φ
r = r θ = θ φ = φ
Note that the operation arctan ( A B ) must be interpreted as the two-argument inverse tangent, atan2 .
Conversion between unit vectors in Cartesian, cylindrical, and spherical coordinate systems in terms of destination coordinates[ 1]
Cartesian
Cylindrical
Spherical
Cartesian
𝐱 ^ = 𝐱 ^ 𝐲 ^ = 𝐲 ^ 𝐳 ^ = 𝐳 ^
𝐱 ^ = cos φ 𝝆 ^ − sin φ 𝝋 ^ 𝐲 ^ = sin φ 𝝆 ^ + cos φ 𝝋 ^ 𝐳 ^ = 𝐳 ^
𝐱 ^ = sin θ cos φ 𝐫 ^ + cos θ cos φ 𝜽 ^ − sin φ 𝝋 ^ 𝐲 ^ = sin θ sin φ 𝐫 ^ + cos θ sin φ 𝜽 ^ + cos φ 𝝋 ^ 𝐳 ^ = cos θ 𝐫 ^ − sin θ 𝜽 ^
Cylindrical
𝝆 ^ = x 𝐱 ^ + y 𝐲 ^ x 2 + y 2 𝝋 ^ = − y 𝐱 ^ + x 𝐲 ^ x 2 + y 2 𝐳 ^ = 𝐳 ^
𝝆 ^ = 𝝆 ^ 𝝋 ^ = 𝝋 ^ 𝐳 ^ = 𝐳 ^
𝝆 ^ = sin θ 𝐫 ^ + cos θ 𝜽 ^ 𝝋 ^ = 𝝋 ^ 𝐳 ^ = cos θ 𝐫 ^ − sin θ 𝜽 ^
Spherical
𝐫 ^ = x 𝐱 ^ + y 𝐲 ^ + z 𝐳 ^ x 2 + y 2 + z 2 𝜽 ^ = ( x 𝐱 ^ + y 𝐲 ^ ) z − ( x 2 + y 2 ) 𝐳 ^ x 2 + y 2 + z 2 x 2 + y 2 𝝋 ^ = − y 𝐱 ^ + x 𝐲 ^ x 2 + y 2
𝐫 ^ = ρ 𝝆 ^ + z 𝐳 ^ ρ 2 + z 2 𝜽 ^ = z 𝝆 ^ − ρ 𝐳 ^ ρ 2 + z 2 𝝋 ^ = 𝝋 ^
𝐫 ^ = 𝐫 ^ 𝜽 ^ = 𝜽 ^ 𝝋 ^ = 𝝋 ^
Conversion between unit vectors in Cartesian, cylindrical, and spherical coordinate systems in terms of source coordinates
Cartesian
Cylindrical
Spherical
Cartesian
𝐱 ^ = 𝐱 ^ 𝐲 ^ = 𝐲 ^ 𝐳 ^ = 𝐳 ^
𝐱 ^ = x 𝝆 ^ − y 𝝋 ^ x 2 + y 2 𝐲 ^ = y 𝝆 ^ + x 𝝋 ^ x 2 + y 2 𝐳 ^ = 𝐳 ^
𝐱 ^ = x ( x 2 + y 2 𝐫 ^ + z 𝜽 ^ ) − y x 2 + y 2 + z 2 𝝋 ^ x 2 + y 2 x 2 + y 2 + z 2 𝐲 ^ = y ( x 2 + y 2 𝐫 ^ + z 𝜽 ^ ) + x x 2 + y 2 + z 2 𝝋 ^ x 2 + y 2 x 2 + y 2 + z 2 𝐳 ^ = z 𝐫 ^ − x 2 + y 2 𝜽 ^ x 2 + y 2 + z 2
Cylindrical
𝝆 ^ = cos φ 𝐱 ^ + sin φ 𝐲 ^ 𝝋 ^ = − sin φ 𝐱 ^ + cos φ 𝐲 ^ 𝐳 ^ = 𝐳 ^
𝝆 ^ = 𝝆 ^ 𝝋 ^ = 𝝋 ^ 𝐳 ^ = 𝐳 ^
𝝆 ^ = ρ 𝐫 ^ + z 𝜽 ^ ρ 2 + z 2 𝝋 ^ = 𝝋 ^ 𝐳 ^ = z 𝐫 ^ − ρ 𝜽 ^ ρ 2 + z 2
Spherical
𝐫 ^ = sin θ ( cos φ 𝐱 ^ + sin φ 𝐲 ^ ) + cos θ 𝐳 ^ 𝜽 ^ = cos θ ( cos φ 𝐱 ^ + sin φ 𝐲 ^ ) − sin θ 𝐳 ^ 𝝋 ^ = − sin φ 𝐱 ^ + cos φ 𝐲 ^
𝐫 ^ = sin θ 𝝆 ^ + cos θ 𝐳 ^ 𝜽 ^ = cos θ 𝝆 ^ − sin θ 𝐳 ^ 𝝋 ^ = 𝝋 ^
𝐫 ^ = 𝐫 ^ 𝜽 ^ = 𝜽 ^ 𝝋 ^ = 𝝋 ^
Table with the del operator in cartesian, cylindrical and spherical coordinates
Operation
Cartesian coordinates (x , y , z )
Cylindrical coordinates (ρ , φ , z )
Spherical coordinates (r , θ , φ ) , where θ is the polar angle and φ is the azimuthal angleα
Vector field A
A x 𝐱 ^ + A y 𝐲 ^ + A z 𝐳 ^
A ρ 𝝆 ^ + A φ 𝝋 ^ + A z 𝐳 ^
A r 𝐫 ^ + A θ 𝜽 ^ + A φ 𝝋 ^
Gradient ∇f [ 1]
∂ f ∂ x 𝐱 ^ + ∂ f ∂ y 𝐲 ^ + ∂ f ∂ z 𝐳 ^
∂ f ∂ ρ 𝝆 ^ + 1 ρ ∂ f ∂ φ 𝝋 ^ + ∂ f ∂ z 𝐳 ^
∂ f ∂ r 𝐫 ^ + 1 r ∂ f ∂ θ 𝜽 ^ + 1 r sin θ ∂ f ∂ φ 𝝋 ^
Divergence ∇ ⋅ A [ 1]
∂ A x ∂ x + ∂ A y ∂ y + ∂ A z ∂ z
1 ρ ∂ ( ρ A ρ ) ∂ ρ + 1 ρ ∂ A φ ∂ φ + ∂ A z ∂ z
1 r 2 ∂ ( r 2 A r ) ∂ r + 1 r sin θ ∂ ∂ θ ( A θ sin θ ) + 1 r sin θ ∂ A φ ∂ φ
Curl ∇ × A [ 1]
( ∂ A z ∂ y − ∂ A y ∂ z ) 𝐱 ^ + ( ∂ A x ∂ z − ∂ A z ∂ x ) 𝐲 ^ + ( ∂ A y ∂ x − ∂ A x ∂ y ) 𝐳 ^
( 1 ρ ∂ A z ∂ φ − ∂ A φ ∂ z ) 𝝆 ^ + ( ∂ A ρ ∂ z − ∂ A z ∂ ρ ) 𝝋 ^ + 1 ρ ( ∂ ( ρ A φ ) ∂ ρ − ∂ A ρ ∂ φ ) 𝐳 ^
1 r sin θ ( ∂ ∂ θ ( A φ sin θ ) − ∂ A θ ∂ φ ) 𝐫 ^ + 1 r ( 1 sin θ ∂ A r ∂ φ − ∂ ∂ r ( r A φ ) ) 𝜽 ^ + 1 r ( ∂ ∂ r ( r A θ ) − ∂ A r ∂ θ ) 𝝋 ^
Laplace operator ∇2 f ≡ ∆f [ 1]
∂ 2 f ∂ x 2 + ∂ 2 f ∂ y 2 + ∂ 2 f ∂ z 2
1 ρ ∂ ∂ ρ ( ρ ∂ f ∂ ρ ) + 1 ρ 2 ∂ 2 f ∂ φ 2 + ∂ 2 f ∂ z 2
1 r 2 ∂ ∂ r ( r 2 ∂ f ∂ r ) + 1 r 2 sin θ ∂ ∂ θ ( sin θ ∂ f ∂ θ ) + 1 r 2 sin 2 θ ∂ 2 f ∂ φ 2
Vector gradient ∇A β
∂ A x ∂ x 𝐱 ^ ⊗ 𝐱 ^ + ∂ A x ∂ y 𝐱 ^ ⊗ 𝐲 ^ + ∂ A x ∂ z 𝐱 ^ ⊗ 𝐳 ^ + ∂ A y ∂ x 𝐲 ^ ⊗ 𝐱 ^ + ∂ A y ∂ y 𝐲 ^ ⊗ 𝐲 ^ + ∂ A y ∂ z 𝐲 ^ ⊗ 𝐳 ^ + ∂ A z ∂ x 𝐳 ^ ⊗ 𝐱 ^ + ∂ A z ∂ y 𝐳 ^ ⊗ 𝐲 ^ + ∂ A z ∂ z 𝐳 ^ ⊗ 𝐳 ^
∂ A ρ ∂ ρ 𝝆 ^ ⊗ 𝝆 ^ + ( 1 ρ ∂ A ρ ∂ φ − A φ ρ ) 𝝆 ^ ⊗ 𝝋 ^ + ∂ A ρ ∂ z 𝝆 ^ ⊗ 𝐳 ^ + ∂ A φ ∂ ρ 𝝋 ^ ⊗ 𝝆 ^ + ( 1 ρ ∂ A φ ∂ φ + A ρ ρ ) 𝝋 ^ ⊗ 𝝋 ^ + ∂ A φ ∂ z 𝝋 ^ ⊗ 𝐳 ^ + ∂ A z ∂ ρ 𝐳 ^ ⊗ 𝝆 ^ + 1 ρ ∂ A z ∂ φ 𝐳 ^ ⊗ 𝝋 ^ + ∂ A z ∂ z 𝐳 ^ ⊗ 𝐳 ^
∂ A r ∂ r 𝐫 ^ ⊗ 𝐫 ^ + ( 1 r ∂ A r ∂ θ − A θ r ) 𝐫 ^ ⊗ 𝜽 ^ + ( 1 r sin θ ∂ A r ∂ φ − A φ r ) 𝐫 ^ ⊗ 𝝋 ^ + ∂ A θ ∂ r 𝜽 ^ ⊗ 𝐫 ^ + ( 1 r ∂ A θ ∂ θ + A r r ) 𝜽 ^ ⊗ 𝜽 ^ + ( 1 r sin θ ∂ A θ ∂ φ − cot θ A φ r ) 𝜽 ^ ⊗ 𝝋 ^ + ∂ A φ ∂ r 𝝋 ^ ⊗ 𝐫 ^ + 1 r ∂ A φ ∂ θ 𝝋 ^ ⊗ 𝜽 ^ + ( 1 r sin θ ∂ A φ ∂ φ + cot θ A θ r + A r r ) 𝝋 ^ ⊗ 𝝋 ^
Vector Laplacian ∇2 A ≡ ∆A [ 2]
∇ 2 A x 𝐱 ^ + ∇ 2 A y 𝐲 ^ + ∇ 2 A z 𝐳 ^
( ∇ 2 A ρ − A ρ ρ 2 − 2 ρ 2 ∂ A φ ∂ φ ) 𝝆 ^ + ( ∇ 2 A φ − A φ ρ 2 + 2 ρ 2 ∂ A ρ ∂ φ ) 𝝋 ^ + ∇ 2 A z 𝐳 ^
( ∇ 2 A r − 2 A r r 2 − 2 r 2 sin θ ∂ ( A θ sin θ ) ∂ θ − 2 r 2 sin θ ∂ A φ ∂ φ ) 𝐫 ^ + ( ∇ 2 A θ − A θ r 2 sin 2 θ + 2 r 2 ∂ A r ∂ θ − 2 cos θ r 2 sin 2 θ ∂ A φ ∂ φ ) 𝜽 ^ + ( ∇ 2 A φ − A φ r 2 sin 2 θ + 2 r 2 sin θ ∂ A r ∂ φ + 2 cos θ r 2 sin 2 θ ∂ A θ ∂ φ ) 𝝋 ^
Directional derivative (A ⋅ ∇)B [ 3]
𝐀 ⋅ ∇ B x 𝐱 ^ + 𝐀 ⋅ ∇ B y 𝐲 ^ + 𝐀 ⋅ ∇ B z 𝐳 ^
( A ρ ∂ B ρ ∂ ρ + A φ ρ ∂ B ρ ∂ φ + A z ∂ B ρ ∂ z − A φ B φ ρ ) 𝝆 ^ + ( A ρ ∂ B φ ∂ ρ + A φ ρ ∂ B φ ∂ φ + A z ∂ B φ ∂ z + A φ B ρ ρ ) 𝝋 ^ + ( A ρ ∂ B z ∂ ρ + A φ ρ ∂ B z ∂ φ + A z ∂ B z ∂ z ) 𝐳 ^
( A r ∂ B r ∂ r + A θ r ∂ B r ∂ θ + A φ r sin θ ∂ B r ∂ φ − A θ B θ + A φ B φ r ) 𝐫 ^ + ( A r ∂ B θ ∂ r + A θ r ∂ B θ ∂ θ + A φ r sin θ ∂ B θ ∂ φ + A θ B r r − A φ B φ cot θ r ) 𝜽 ^ + ( A r ∂ B φ ∂ r + A θ r ∂ B φ ∂ θ + A φ r sin θ ∂ B φ ∂ φ + A φ B r r + A φ B θ cot θ r ) 𝝋 ^
Tensor divergence ∇ ⋅ T γ
( ∂ T x x ∂ x + ∂ T y x ∂ y + ∂ T z x ∂ z ) 𝐱 ^ + ( ∂ T x y ∂ x + ∂ T y y ∂ y + ∂ T z y ∂ z ) 𝐲 ^ + ( ∂ T x z ∂ x + ∂ T y z ∂ y + ∂ T z z ∂ z ) 𝐳 ^
[ ∂ T ρ ρ ∂ ρ + 1 ρ ∂ T φ ρ ∂ φ + ∂ T z ρ ∂ z + 1 ρ ( T ρ ρ − T φ φ ) ] 𝝆 ^ + [ ∂ T ρ φ ∂ ρ + 1 ρ ∂ T φ φ ∂ φ + ∂ T z φ ∂ z + 1 ρ ( T ρ φ + T φ ρ ) ] 𝝋 ^ + [ ∂ T ρ z ∂ ρ + 1 ρ ∂ T φ z ∂ φ + ∂ T z z ∂ z + T ρ z ρ ] 𝐳 ^
[ ∂ T r r ∂ r + 2 T r r r + 1 r ∂ T θ r ∂ θ + cot θ r T θ r + 1 r sin θ ∂ T φ r ∂ φ − 1 r ( T θ θ + T φ φ ) ] 𝐫 ^ + [ ∂ T r θ ∂ r + 2 T r θ r + 1 r ∂ T θ θ ∂ θ + cot θ r T θ θ + 1 r sin θ ∂ T φ θ ∂ φ + T θ r r − cot θ r T φ φ ] 𝜽 ^ + [ ∂ T r φ ∂ r + 2 T r φ r + 1 r ∂ T θ φ ∂ θ + 1 r sin θ ∂ T φ φ ∂ φ + T φ r r + cot θ r ( T θ φ + T φ θ ) ] 𝝋 ^
^α This page uses θ for the polar angle and φ for the azimuthal angle, which is common notation in physics. The source that is used for these formulae uses θ for the azimuthal angle and φ for the polar angle, which is common mathematical notation . In order to get the mathematics formulae, switch θ and φ in the formulae shown in the table above.^β Defined in Cartesian coordinates as ∂ i 𝐀 ⊗ 𝐞 i . An alternative definition is 𝐞 i ⊗ ∂ i 𝐀 .^γ Defined in Cartesian coordinates as 𝐞 i ⋅ ∂ i 𝐓 . An alternative definition is ∂ i 𝐓 ⋅ 𝐞 i .
div grad f ≡ ∇ ⋅ ∇ f ≡ ∇ 2 f
curl grad f ≡ ∇ × ∇ f = 𝟎
div curl 𝐀 ≡ ∇ ⋅ ( ∇ × 𝐀 ) = 0
curl curl 𝐀 ≡ ∇ × ( ∇ × 𝐀 ) = ∇ ( ∇ ⋅ 𝐀 ) − ∇ 2 𝐀 (Lagrange's formula for del)
∇ 2 ( f g ) = f ∇ 2 g + 2 ∇ f ⋅ ∇ g + g ∇ 2 f
∇ 2 ( 𝐏 ⋅ 𝐐 ) = 𝐐 ⋅ ∇ 2 𝐏 − 𝐏 ⋅ ∇ 2 𝐐 + 2 ∇ ⋅ [ ( 𝐏 ⋅ ∇ ) 𝐐 + 𝐏 × ∇ × 𝐐 ] (From [ 4] )
File:Nabla cartesian.svg
div 𝐀 = lim V → 0 ∬ ∂ V 𝐀 ⋅ d 𝐒 ∭ V d V = [ A x ( x + d x ) − A x ( x ) ] d y d z + [ A y ( y + d y ) − A y ( y ) ] d x d z + [ A z ( z + d z ) − A z ( z ) ] d x d y d x d y d z = ∂ A x ∂ x + ∂ A y ∂ y + ∂ A z ∂ z
( curl 𝐀 ) x = lim S ⊥ 𝐱 ^ → 0 ∫ ∂ S 𝐀 ⋅ d ℓ ∬ S d S = [ A z ( y + d y ) − A z ( y ) ] d z − [ A y ( z + d z ) − A y ( z ) ] d y d y d z = ∂ A z ∂ y − ∂ A y ∂ z
The expressions for ( curl 𝐀 ) y and ( curl 𝐀 ) z are found in the same way.
File:Nabla cylindrical2.svg
div 𝐀 = lim V → 0 ∬ ∂ V 𝐀 ⋅ d 𝐒 ∭ V d V = [ A ρ ( ρ + d ρ ) ( ρ + d ρ ) − A ρ ( ρ ) ρ ] d ϕ d z + [ A ϕ ( ϕ + d ϕ ) − A ϕ ( ϕ ) ] d ρ d z + [ A z ( z + d z ) − A z ( z ) ] d ρ ( ρ + d ρ / 2 ) d ϕ ρ d ϕ d ρ d z = 1 ρ ∂ ( ρ A ρ ) ∂ ρ + 1 ρ ∂ A ϕ ∂ ϕ + ∂ A z ∂ z
( curl 𝐀 ) ρ = lim S ⊥ 𝝆 ^ → 0 ∫ ∂ S 𝐀 ⋅ d ℓ ∬ S d S = A ϕ ( z ) ( ρ + d ρ ) d ϕ − A ϕ ( z + d z ) ( ρ + d ρ ) d ϕ + A z ( ϕ + d ϕ ) d z − A z ( ϕ ) d z ( ρ + d ρ ) d ϕ d z = − ∂ A ϕ ∂ z + 1 ρ ∂ A z ∂ ϕ
( curl 𝐀 ) ϕ = lim S ⊥ 𝝓 ^ → 0 ∫ ∂ S 𝐀 ⋅ d ℓ ∬ S d S = A z ( ρ ) d z − A z ( ρ + d ρ ) d z + A ρ ( z + d z ) d ρ − A ρ ( z ) d ρ d ρ d z = − ∂ A z ∂ ρ + ∂ A ρ ∂ z
( curl 𝐀 ) z = lim S ⊥ 𝒛 ^ → 0 ∫ ∂ S 𝐀 ⋅ d ℓ ∬ S d S = A ρ ( ϕ ) d ρ − A ρ ( ϕ + d ϕ ) d ρ + A ϕ ( ρ + d ρ ) ( ρ + d ρ ) d ϕ − A ϕ ( ρ ) ρ d ϕ ρ d ρ d ϕ = − 1 ρ ∂ A ρ ∂ ϕ + 1 ρ ∂ ( ρ A ϕ ) ∂ ρ
curl 𝐀 = ( curl 𝐀 ) ρ 𝝆 ^ + ( curl 𝐀 ) ϕ 𝝓 ^ + ( curl 𝐀 ) z 𝒛 ^ = ( 1 ρ ∂ A z ∂ ϕ − ∂ A ϕ ∂ z ) 𝝆 ^ + ( ∂ A ρ ∂ z − ∂ A z ∂ ρ ) 𝝓 ^ + 1 ρ ( ∂ ( ρ A ϕ ) ∂ ρ − ∂ A ρ ∂ ϕ ) 𝒛 ^
File:Nabla spherical2.svg
div 𝐀 = lim V → 0 ∬ ∂ V 𝐀 ⋅ d 𝐒 ∭ V d V = [ A r ( r + d r ) ( r + d r ) 2 − A r ( r ) r 2 ] sin θ d θ d ϕ + [ A θ ( θ + d θ ) sin ( θ + d θ ) − A θ ( θ ) sin θ ] r d r d ϕ + [ A ϕ ( ϕ + d ϕ ) − A ϕ ( ϕ ) ] r d r d θ d r r d θ r sin θ d ϕ = 1 r 2 ∂ ( r 2 A r ) ∂ r + 1 r sin θ ∂ ( A θ sin θ ) ∂ θ + 1 r sin θ ∂ A ϕ ∂ ϕ
( curl 𝐀 ) r = lim S ⊥ 𝒓 ^ → 0 ∫ ∂ S 𝐀 ⋅ d ℓ ∬ S d S = A θ ( ϕ ) r d θ + A ϕ ( θ + d θ ) r sin ( θ + d θ ) d ϕ − A θ ( ϕ + d ϕ ) r d θ − A ϕ ( θ ) r sin ( θ ) d ϕ r d θ r sin θ d ϕ = 1 r sin θ ∂ ( A ϕ sin θ ) ∂ θ − 1 r sin θ ∂ A θ ∂ ϕ
( curl 𝐀 ) θ = lim S ⊥ 𝜽 ^ → 0 ∫ ∂ S 𝐀 ⋅ d ℓ ∬ S d S = A ϕ ( r ) r sin θ d ϕ + A r ( ϕ + d ϕ ) d r − A ϕ ( r + d r ) ( r + d r ) sin θ d ϕ − A r ( ϕ ) d r d r r sin θ d ϕ = 1 r sin θ ∂ A r ∂ ϕ − 1 r ∂ ( r A ϕ ) ∂ r
( curl 𝐀 ) ϕ = lim S ⊥ 𝝓 ^ → 0 ∫ ∂ S 𝐀 ⋅ d ℓ ∬ S d S = A r ( θ ) d r + A θ ( r + d r ) ( r + d r ) d θ − A r ( θ + d θ ) d r − A θ ( r ) r d θ r d r d θ = 1 r ∂ ( r A θ ) ∂ r − 1 r ∂ A r ∂ θ
curl 𝐀 = ( curl 𝐀 ) r 𝒓 ^ + ( curl 𝐀 ) θ 𝜽 ^ + ( curl 𝐀 ) ϕ 𝝓 ^ = 1 r sin θ ( ∂ ( A ϕ sin θ ) ∂ θ − ∂ A θ ∂ ϕ ) 𝒓 ^ + 1 r ( 1 sin θ ∂ A r ∂ ϕ − ∂ ( r A ϕ ) ∂ r ) 𝜽 ^ + 1 r ( ∂ ( r A θ ) ∂ r − ∂ A r ∂ θ ) 𝝓 ^
The unit vector of a coordinate parameter u is defined in such a way that a small positive change in u causes the position vector 𝐫 to change in 𝐮 direction.
Therefore,
∂ 𝐫 ∂ u = ∂ s ∂ u 𝐮
where s is the arc length parameter.
For two sets of coordinate systems u i and v j , according to chain rule ,
d 𝐫 = ∑ i ∂ 𝐫 ∂ u i d u i = ∑ i ∂ s ∂ u i 𝐮 ^ i d u i = ∑ j ∂ s ∂ v j 𝐯 ^ j d v j = ∑ j ∂ s ∂ v j 𝐯 ^ j ∑ i ∂ v j ∂ u i d u i = ∑ i ∑ j ∂ s ∂ v j ∂ v j ∂ u i 𝐯 ^ j d u i .
Now, we isolate the i th component. For i ≠ k , let d u k = 0 . Then divide on both sides by d u i to get:
∂ s ∂ u i 𝐮 ^ i = ∑ j ∂ s ∂ v j ∂ v j ∂ u i 𝐯 ^ j .
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^ Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
^ Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
^ Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).