Integral over a 3-D domain
Part of a series of articles about |
Calculus |
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- Rolle's theorem
- Mean value theorem
- Inverse function theorem
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Differential Definitions |
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| Concepts |
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- Differentiation notation
- Second derivative
- Implicit differentiation
- Logarithmic differentiation
- Related rates
- Taylor's theorem
| Rules and identities |
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| Definitions |
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| Integration by |
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In mathematics (particularly multivariable calculus), a volume integral (∭) is an integral over a 3-dimensional domain; that is, it is a special case of multiple integrals. Volume integrals are especially important in physics for many applications, for example, to calculate flux densities, or to calculate mass from a corresponding density function.
In coordinates
It can also mean a triple integral within a region of a function and is usually written as:
A volume integral in cylindrical coordinates is
and a volume integral in
spherical coordinates (using the ISO convention for angles with
as the azimuth and
measured from the polar axis (see more on
conventions)) has the form
Example
Integrating the equation over a unit cube yields the following result:
So the volume of the unit cube is 1 as expected. This is rather trivial however, and a volume integral is far more powerful. For instance if we have a scalar density function on the unit cube then the volume integral will give the total mass of the cube. For example for density function:
the total mass of the cube is:
See also
- Mathematics portal
External links