Del_in_cylindrical_and_spherical_coordinates

Del in cylindrical and spherical coordinates

This is a list of some vector calculus formulae of general use in working with various coordinate systems.

Note

  • This page uses standard physics notation. For spherical coordinates, theta is the angle between the z axis and the radius vector connecting the origin to the point in question. phi is the angle between the projection of the radius vector onto the x-y plane and the x axis. Some (American mathematics) sources reverse this definition.
  • The function atan2(y, x) is used instead of the mathematical function arctan(y/x) due to its domain and image. The classical arctan(y/x) has an image of (-π/2, +π/2), whereas atan2(y, x) is defined to have an image of (-π, π]. (The expressions for the Nabla in spherical coordinates may need to be corrected)

Table with the del operator in cylindrical, spherical and parabolic cylindrical coordinates
Operation Cartesian coordinates (x,y,z) Cylindrical coordinates (s,φ,z) Spherical coordinates (r,θ,φ) Parabolic cylindrical coordinates (ο,τ,z)

Definition
of
coordinates

begin{matrix} s & = & sqrt{x^2+y^2}
   phi & = & arctan(y/x) 
z & = & z end{matrix}

begin{matrix}
   x & = & scosphi 
   y & = & ssinphi 
z & = & z end{matrix}

begin{matrix}
   x & = & rsinthetacosphi 
   y & = & rsinthetasinphi 
z & = & rcostheta end{matrix}

begin{matrix}
   x & = & sigma tau
y & = & frac{1}{2} left(tau^{2} - sigma^{2} right) z & = & z end{matrix}

begin{matrix} r & = & sqrt{x^2+y^2+z^2} theta & = & arctan{left(frac{sqrt{x^2+y^2}}{z}right)} phi & = & arctan(y/x) end{matrix}

begin{matrix} r & = & sqrt{s^2 + z^2} theta & = & arctan{(s/z)} phi & = & phi end{matrix}

begin{matrix}
   s & = & rsin(theta) 
   phi & = & phi
z & = & rcos(theta) end{matrix}

begin{matrix}
   scosphi & = & sigma tau
ssinphi & = & frac{1}{2} left(tau^{2} - sigma^{2} right) z & = & z end{matrix}

Definition
of
unit
vectors

begin{matrix} boldsymbol{hat s} & = & frac{x}{s}mathbf{hat x}+frac{y}{s}mathbf{hat y} boldsymbol{hatphi} & = & -frac{y}{s}mathbf{hat x}+frac{x}{s}mathbf{hat y} mathbf{hat z} & = & mathbf{hat z} end{matrix}

begin{matrix} mathbf{hat x} & = & cosphiboldsymbol{hat s}-sinphiboldsymbol{hatphi} mathbf{hat y} & = & sinphiboldsymbol{hat s}+cosphiboldsymbol{hatphi} mathbf{hat z} & = & mathbf{hat z} end{matrix}

begin{matrix} mathbf{hat x} & = & sinthetacosphiboldsymbol{hat r}+costhetacosphiboldsymbol{hattheta}-sinphiboldsymbol{hatphi} mathbf{hat y} & = & sinthetasinphiboldsymbol{hat r}+costhetasinphiboldsymbol{hattheta}+cosphiboldsymbol{hatphi} mathbf{hat z} & = & costheta boldsymbol{hat r}-sintheta boldsymbol{hattheta} end{matrix}

begin{matrix} boldsymbol{hat sigma} & = & frac{tau}{sqrt{tau^2+sigma^2}}mathbf{hat x}-frac{sigma}{sqrt{tau^2+sigma^2}}mathbf{hat y} boldsymbol{hattau} & = & frac{sigma}{sqrt{tau^2+sigma^2}}mathbf{hat x}+frac{tau}{sqrt{tau^2+sigma^2}}mathbf{hat y} mathbf{hat z} & = & mathbf{hat z} end{matrix}

begin{matrix} mathbf{hat r} & = & frac{xmathbf{hat x}+ymathbf{hat y}+zmathbf{hat z}}{r} boldsymbol{hattheta} & = & frac{xzmathbf{hat x}+yzmathbf{hat y}-s^2mathbf{hat z}}{r s} boldsymbol{hatphi} & = & frac{-ymathbf{hat x}+xmathbf{hat y}}{s} end{matrix}

begin{matrix} mathbf{hat r} & = & frac{s}{r}boldsymbol{hat s}+frac{ z}{r}mathbf{hat z} boldsymbol{hattheta} & = & frac{z }{r}boldsymbol{hat s}-frac{s}{r}mathbf{hat z} boldsymbol{hatphi} & = & boldsymbol{hatphi} end{matrix}

begin{matrix} boldsymbol{hat s} & = & sinthetamathbf{hat r}+costhetaboldsymbol{hattheta} boldsymbol{hatphi} & = & boldsymbol{hatphi} mathbf{hat z} & = & costhetamathbf{hat r}-sinthetaboldsymbol{hattheta} end{matrix}

begin{matrix} end{matrix}

A vector field mathbf{A} A_xmathbf{hat x} + A_ymathbf{hat y} + A_zmathbf{hat z} A_sboldsymbol{hat s} + A_phiboldsymbol{hat phi} + A_zboldsymbol{hat z} A_rboldsymbol{hat r} + A_thetaboldsymbol{hat theta} + A_phiboldsymbol{hat phi} A_sigmaboldsymbol{hat sigma} + A_tauboldsymbol{hat tau} + A_phiboldsymbol{hat z}

Gradient nabla f

{partial f over partial x}mathbf{hat x} + {partial f over partial y}mathbf{hat y} + {partial f over partial z}mathbf{hat z}

{partial f over partial s}boldsymbol{hat s} + {1 over s}{partial f over partial phi}boldsymbol{hat phi} + {partial f over partial z}boldsymbol{hat z}

{partial f over partial r}boldsymbol{hat r} + {1 over r}{partial f over partial theta}boldsymbol{hat theta} + {1 over rsintheta}{partial f over partial phi}boldsymbol{hat phi}

frac{1}{sqrt{sigma^{2} + tau^{2}}} {partial f over partial sigma}boldsymbol{hat sigma} + frac{1}{sqrt{sigma^{2} + tau^{2}}} {partial f over partial tau}boldsymbol{hat tau} + {partial f over partial z}boldsymbol{hat z}

Divergence nabla cdot mathbf{A}

{partial A_x over partial x} + {partial A_y over partial y} + {partial A_z over partial z}

{1 over s}{partial left(s A_s right) over partial s} + {1 over s}{partial A_phi over partial phi} + {partial A_z over partial z}

{1 over r^2}{partial left(r^2 A_r right) over partial r} + {1 over rsintheta}{partial over partial theta} left( A_thetasintheta right) + {1 over rsintheta}{partial A_phi over partial phi}

frac{1}{sigma^{2} + tau^{2}}{partial A_sigma over partial sigma} + frac{1}{sigma^{2} + tau^{2}}{partial A_tau over partial tau} + {partial A_z over partial z}

Curl nabla times mathbf{A}

begin{matrix} displaystyleleft({partial A_z over partial y} - {partial A_y over partial z}right) mathbf{hat x} & + displaystyleleft({partial A_x over partial z} - {partial A_z over partial x}right) mathbf{hat y} & + displaystyleleft({partial A_y over partial x} - {partial A_x over partial y}right) mathbf{hat z} & end{matrix}

begin{matrix} displaystyleleft({1 over s}{partial A_z over partial phi} - {partial A_phi over partial z}right) boldsymbol{hat s} & + displaystyleleft({partial A_s over partial z} - {partial A_z over partial s}right) boldsymbol{hat phi} & + displaystyle{1 over s}left({partial left(s A_phi right) over partial s} - {partial A_s over partial phi}right) boldsymbol{hat z} & end{matrix}

begin{matrix} displaystyle{1 over rsintheta}left({partial over partial theta} left(A_phisintheta right) - {partial A_theta over partial phi}right) boldsymbol{hat r} & + displaystyle{1 over r}left({1 over sintheta}{partial A_r over partial phi} - {partial over partial r} left(r A_phi right) right) boldsymbol{hat theta} & + displaystyle{1 over r}left({partial over partial r} left(r A_theta right) - {partial A_r over partial theta}right) boldsymbol{hat phi} & end{matrix}

begin{matrix} displaystyleleft(frac{1}{sqrt{sigma^{2} + tau^{2}}}{partial A_z over partial tau} - {partial A_tau over partial z}right) boldsymbol{hat sigma} & - displaystyleleft(frac{1}{sqrt{sigma^{2} + tau^{2}}}{partial A_z over partial sigma}- {partial A_sigma over partial z}right) boldsymbol{hat tau} & + displaystylefrac{1}{sqrt{sigma^{2} + tau^{2}}}left({partial left(s A_phi right) over partial s} - {partial A_s over partial phi}right) boldsymbol{hat z} & end{matrix}

Laplace operator Delta f = nabla^2 f

{partial^2 f over partial x^2} + {partial^2 f over partial y^2} + {partial^2 f over partial z^2}

{1 over s}{partial over partial s}left(s {partial f over partial s}right) + {1 over s^2}{partial^2 f over partial phi^2} + {partial^2 f over partial z^2}

{1 over r^2}{partial over partial r}!left(r^2 {partial f over partial r}right) !+!{1 over r^2!sintheta}{partial over partial theta}!left(sintheta {partial f over partial theta}right) !+!{1 over r^2!sin^2theta}{partial^2 f over partial phi^2}

frac{1}{sigma^{2} + tau^{2}} left( frac{partial^{2} f}{partial sigma^{2}} + frac{partial^{2} f}{partial tau^{2}} right) + frac{partial^{2} f}{partial z^{2}}

Vector Laplacian Delta mathbf{A} = nabla^2 mathbf{A}

Delta A_x mathbf{hat x} + Delta A_y mathbf{hat y} + Delta A_z mathbf{hat z}

begin{matrix} displaystyleleft(Delta A_s - {A_s over s^2} - {2 over s^2}{partial A_phi over partial phi}right) boldsymbol{hat s} & + displaystyleleft(Delta A_phi - {A_phi over s^2} + {2 over s^2}{partial A_s over partial phi}right) boldsymbol{hatphi} & + displaystyleleft(Delta A_z right) boldsymbol{hat z} & end{matrix}

begin{matrix} left(Delta A_r - {2 A_r over r^2} - {2 over r^2sintheta}{partial left(A_theta sinthetaright) over partialtheta} - {2 over r^2sintheta}{partial A_phi over partial phi}right) boldsymbol{hat r} & + left(Delta A_theta - {A_theta over r^2sin^2theta} + {2 over r^2}{partial A_r over partial theta} - {2 costheta over r^2sin^2theta}{partial A_phi over partial phi}right) boldsymbol{hattheta} & + left(Delta A_phi - {A_phi over r^2sin^2theta} + {2 over r^2sintheta}{partial A_r over partial phi} + {2 costheta over r^2sin^2theta}{partial A_theta over partial phi}right) boldsymbol{hatphi} & end{matrix}

Differential displacement

dmathbf{l} = dxmathbf{hat x} + dymathbf{hat y} + dzmathbf{hat z}

dmathbf{l} = dsboldsymbol{hat s} + s dphiboldsymbol{hat phi} + dzboldsymbol{hat z}

dmathbf{l} = drmathbf{hat r} + rdthetaboldsymbol{hat theta} + rsintheta dphiboldsymbol{hat phi}

dmathbf{l} = sqrt{sigma^{2} + tau^{2}} dsigmaboldsymbol{hat sigma} + sqrt{sigma^{2} + tau^{2}} dtauboldsymbol{hat tau} + dzboldsymbol{hat z}

Differential normal area

begin{matrix}dmathbf{S} = &dy,dz,mathbf{hat x} + &dx,dz,mathbf{hat y} + &dx,dy,mathbf{hat z}end{matrix}

begin{matrix} dmathbf{S} = & s, dphi, dz,boldsymbol{hat s} + & ds ,dz,boldsymbol{hat phi} + & s ,ds dphi ,mathbf{hat z} end{matrix}

begin{matrix} dmathbf{S} = & r^2 sintheta ,dtheta ,dphi ,mathbf{hat r} + & rsintheta ,dr,dphi ,boldsymbol{hat theta} + & r,dr,dtheta,boldsymbol{hat phi} end{matrix}

begin{matrix} dmathbf{S} = & sqrt{sigma^{2} + tau^{2}}, dtau, dz,boldsymbol{hat sigma} + & sqrt{sigma^{2} + tau^{2}} dsigma,dz,boldsymbol{hat tau} + & sigma^{2} + tau^{2} dsigma, dtau ,mathbf{hat z} end{matrix}

Differential volume

dtau = dx,dy,dz ,

dtau = s, ds, dphi, dz,

dtau = r^2sintheta ,dr,dtheta, dphi,

dtau = left(sigma^{2} + tau^{2} right) dsigma dtau dz,

Non-trivial calculation rules:
  1. operatorname{div grad } f = nabla cdot (nabla f) = nabla^2 f = Delta f (Laplacian)
  2. operatorname{curl grad } f = nabla times (nabla f) = mathbf{0}
  3. operatorname{div curl } mathbf{A} = nabla cdot (nabla times mathbf{A}) = 0
  4. operatorname{curl curl } mathbf{A} = nabla times (nabla times mathbf{A}) = nabla (nabla cdot mathbf{A}) - nabla^2 mathbf{A} (using Lagrange's formula for the cross product)
  5. Delta f g = f Delta g + 2 nabla f cdot nabla g + g Delta f

See also

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