# SurfaceIntegrate

SurfaceIntegrate[f,{x,y,}surface]

computes the scalar surface integral of the function f[x,y,] over the surface.

SurfaceIntegrate[{p,q,},{x,y,}surface]

computes the vector surface integral of the vector field {p[x,y,],q[x,y,],}.

# Details and Options    • Surface integrals are also known as flux integrals.
• Scalar surface integrals integrate scalar functions over a hypersurface. They are typically used to compute things like area, mass and charge for a surface.
• Vector surface integrals are used to compute the flux of a vector function through a surface in the direction of its normal. Typical vector functions include a fluid velocity field, electric field and magnetic field.
• The scalar surface integral of a function f over a surface is given by:
• • where is the measure of a parametric surface element.
• The scalar surface integral of f over a hypersurface is given by:
• • The scalar surface integral is independent of the parametrization and orientation of the surface. Any dimensional RegionQ object in can be use for the surface.
• The vector surface integral of a vector function over a surface is given by:
• • where is the projection of the vector function onto the normal direction so only the component in the normal direction gets integrated.
• The vector surface integral of over a a hypersurface is given by:
• • The vector surface integral is independent of the parametrization, but depends on the orientation.
• The orientation for a hypersurface is given by a normal vector field over the surface.
• • For a parametric hypersurface ParametricRegion[{r1[u1,,un-1],,rn[u1,,un-1]},], the normal vector field is taken to be Cross[u1r[u],,un-1r[u]].
• The RegionQ objects in Wolfram Language are not oriented. However for the convenience of this function, you can assume the following rules for getting oriented hypersurfaces.
• For solid (of dimension ) and bounded RegionQ objects , take the surface to be the region boundary () and the normal orientation to be pointed outward.
• Special solids in with their assumed boundary surface (edge) normal orientation include:
• Triangle outward normal Rectangle outward normal Polygon outward normal Disk outward normal Ellipsoid outward normal Annulus outward normal
• Special solids in with their assumed boundary surface (face) normal orientation include:
• Tetrahedron outward normal Cuboid outward normal Polyhedron outward normal Ball outward normal Ellipsoid outward normal Cylinder outward normal Cone outward normal
• Special solids in with their assumed surface (facet) and normal orientation:
• Simplex outward normal Cuboid outward normal Ball outward normal Ellipsoid outward normal
• The following options can be given:
•  AccuracyGoal Automatic digits of absolute accuracy sought Assumptions \$Assumptions assumptions to make about parameters GenerateConditions Automatic whether to generate answers that involve conditions on parameters GeneratedParameters None how to name generated parameters Method Automatic method to use PerformanceGoal \$PerformanceGoal aspects of performance to optimize PrecisionGoal Automatic digits of precision sought PrincipalValue False whether to find Cauchy principal values WorkingPrecision Automatic the precision used in internal computations
• SurfaceIntegrate uses a combination of symbolic and numerical methods when the input involves inexact quantities.

# Examples

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## Basic Examples(6)

Surface integral of a scalar function over a spherical surface:

Surface integral of a vector field over a spherical surface:

Surface integral of a scalar field over a parametric surface:

Surface integral of a vector field over a parametric surface:

Surface integral of a scalar field over a surface:

Visualize the scalar field on the surface:

Surface integral of a vector field over a surface:

Visualize the scalar field on the surface:

## Scope(32)

### Basic Uses(5)

Surface integral of a scalar field over a sphere in three dimensions:

Surface integral of a vector field in three dimensions:

SurfaceIntegrate works with many special surfaces:

Surface integral over a parametric surface:

SurfaceIntegrate works in dimensions different from three:

### Scalar Functions(5)

Surface integral of a scalar field over a three-dimensional surface:

Plot of the surface:

Surface integral:

Surface integral of a scalar field:

The surface integral:

Surface integral of a scalar field in three dimensions over a sphere:

Surface integral of a scalar field over the surface of a pyramid:

Surface integral:

Surface integral of a scalar field over a parametric surface in three dimensions:

The surface and its plot:

### Vector Functions(5)

Surface integral of a vector field in three dimensions over a sphere:

Visualize the vector field on the surface:

Surface integral:

Surface integral of a vector field in three dimensions over a triangle:

Surface integral:

Surface integral of a vector field over a parametric surface in three dimensions:

Surface integral of a vector field over the boundary of an ellipsoid:

Surface integral of a vector field in three dimensions over the boundary of a cone:

Visualization of the vector field on the surface:

Surface integral:

### Special Surfaces(10)

Surface integral of a vector field over a sphere of radius :

Surface integral of a vector field over the boundary of a cube of side centered at the origin:

Surface integral of a vector field over the boundary of a tetrahedron:

Surface integral of a vector field over a triangle:

Surface integral of a vector field over an ellipsoid:

Surface integral of a vector field over the boundary of a cone:

Surface integral of a vector field over the boundary of a cylinder:

Surface integral of a vector field over the boundary of a parallelepiped:

Surface integral of a vector field over the boundary of a prism:

Surface integral over a polygon in three dimensions:

The orientation of the polygon depends on the order in which the points are given:

### Parametric Surfaces(4)

Surface integral of a vector field over a parametric surface:

Surface integral of a vector field over a parametrized dome-like surface:

Surface integral over a parametrized cylinder:

Surface integral of a vector field over a parametrized hyperboloid:

### Hypersurfaces(3)

Surface integral over a 1D hypersurface in 2D:

Surface integral over a 3D hypersurface in 4D:

Volume of a five-dimensional sphere, computed using a surface integral:

## Options(3)

### GenerateConditions(1)

SurfaceIntegrate can work with symbolic parameters:

Generate conditions on the parameters:

### WorkingPrecision(2)

If a WorkingPrecision is specified, a numerical result is given:

The result has finite precision if the integrand has a finite precision:

## Applications(15)

### College Calculus(4)

Surface integral over the boundary of a cube of side 2 centered at the origin:

Surface integral over a paraboloid:

Surface integral over a hemispherical shell of radius :

Surface integral over the boundary of a cube:

### Areas(3)

Area of a sphere:

Area of an ellipsoid:

Area of a triangle:

### Volumes(3)

Volume of an ellipsoid computed using a surface integral:

Volume of a icosahedron computed using a surface integral:

Volume of a cube of side computed using a surface integral:

### Flux(3)

Flux of the electric field generated by a point charge at the origin over a sphere surrounding it:

Flux of the uniform magnetic field of an infinite solenoid with windings per unit length traversed by a current over a disk orthogonal to it:

Electric field due to an infinite charged wire of linear charge density :

Flux across a cylinder of height and radius having the axis on the charged wire:

### Centroids(2)

Mass of a hemispherical shell of unit density and radius : coordinate of the center of mass: coordinate of the center of mass: coordinate of the center of mass:

Moments of inertia of a thin cut cone:

About the axis:

About the axis:

About the axis:

## Properties & Relations(5)

Apply N[SurfaceIntegrate[...]] to obtain a numerical solution if the symbolic calculation fails:

Find the center of mass of a thin triangular surface of unit mass per unit area:

Find the total mass:

Find the component of the center of mass:

Find the component of the center of mass:

Find the component of the center of mass:

The center of mass can also be obtained using RegionCentroid:

Find the moment of inertia around the axis of a thin cylindrical shell of unit area density:

The answer can also be computed with MomentOfInertia:

Find the area of a tetrahedron:

The answer can also be computed with Area:

Find the volume of a icosahedron:

The answer can also be computed with Volume:

## Neat Examples(4)

Volume of a pseudosphere computed using a surface integral:

Plot of a finite part of the pseudosphere:

Volume of a Dupin cyclide:

Flux of a vector field across a part of a Bohemian dome:

Compute numerically the area of Guimard's surface: