# NSurfaceIntegrate

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

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

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

computes the numerical 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, an electric field and a 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 orientations 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 orientations 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 orientations:
•  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 MaxPoints Automatic maximum total number of sample points MaxRecursion Automatic maximum number of recursive subdivisions Method Automatic method to use MinRecursion 0 minimum number of recursive subdivisions PrecisionGoal Automatic digits of precision sought WorkingPrecision Automatic the precision used in internal computations

# 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 cube 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 over a triangle:

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 1:

Surface integral of a vector field over the boundary of a cube of side 2 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(8)

### AccuracyGoal(1)

The option AccuracyGoal sets the number of digits of accuracy:

The result with default settings only sets a PrecisionGoal:

### MaxPoints(1)

The option MaxPoints stops the integration after a specified number of points has been evaluated:

With default options:

### MaxRecursion(1)

The option MaxRecursion specifies the maximum number of recursive steps:

Increasing the number of recursions:

### Method(1)

The option Method can take the same values as in NIntegrate. For example:

With default options:

### MinRecursion(1)

Useful for sharply peaked functions, the option MinRecursion forces a minimum number of subdivisions:

Compare to the exact result:

### PrecisionGoal(1)

The option PrecisionGoal sets the relative tolerance in the integration:

With default settings:

### WorkingPrecision(2)

If a WorkingPrecision is specified, the calculation is done with that working precision:

The integrand may have a finite precision:

## Applications(18)

### College Calculus(5)

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

Surface integral over a paraboloid:

Surface integral over the side of a cylinder:

Surface integral over a hemispherical shell of radius 2:

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 an icosahedron computed using a surface integral:

Volume of a cube of side 3 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:

### Classical Theorems(2)

Stokes's theorem. The surface integral of the Curl of a vector field :

The surface integral of over an open surface is:

It is the same as the line integral of over the boundary of the surface:

Divergence theorem. The surface integral of a vector field (with continuous partial derivatives) over a closed surface is:

It is the same as the integral of Div[f] over the interior of the surface:

## Properties & Relations(5)

Apply N[SurfaceIntegrate[]] to obtain a numerical solution with NSurfaceIntegrate 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 SurfaceArea:

Find the volume of an icosahedron:

The answer can also be computed with Volume:

## Neat Examples(9)

Volume of a pseudosphere computed using a surface integral:

Plot of a finite part of the pseudosphere:

Volume of a drop-shaped solid using a surface integral:

Volume of a Dupin cyclide:

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

Surface integral of a vector field over a portion of a conocuneus of Wallis:

Surface integral of a vector field over a funnel-shaped surface:

Area of a Gaudi surface:

Compute numerically the area of Guimard's surface:

Surface integral of a vector field over a Neiloid:

Wolfram Research (2023), NSurfaceIntegrate, Wolfram Language function, https://reference.wolfram.com/language/ref/NSurfaceIntegrate.html.

#### Text

Wolfram Research (2023), NSurfaceIntegrate, Wolfram Language function, https://reference.wolfram.com/language/ref/NSurfaceIntegrate.html.

#### CMS

Wolfram Language. 2023. "NSurfaceIntegrate." Wolfram Language & System Documentation Center. Wolfram Research. https://reference.wolfram.com/language/ref/NSurfaceIntegrate.html.

#### APA

Wolfram Language. (2023). NSurfaceIntegrate. Wolfram Language & System Documentation Center. Retrieved from https://reference.wolfram.com/language/ref/NSurfaceIntegrate.html

#### BibTeX

@misc{reference.wolfram_2024_nsurfaceintegrate, author="Wolfram Research", title="{NSurfaceIntegrate}", year="2023", howpublished="\url{https://reference.wolfram.com/language/ref/NSurfaceIntegrate.html}", note=[Accessed: 14-July-2024 ]}

#### BibLaTeX

@online{reference.wolfram_2024_nsurfaceintegrate, organization={Wolfram Research}, title={NSurfaceIntegrate}, year={2023}, url={https://reference.wolfram.com/language/ref/NSurfaceIntegrate.html}, note=[Accessed: 14-July-2024 ]}