When the function to be integrated has a cylindrical symmetry, it is sensible to change the variables into cylindrical coordinates and then perform integration.

In R^{3} the integration on domains with a circular base can be made by the *passage in cylindrical coordinates *; the transformation of the function is made by the following relation: *(dx dy dz) *differentials in the integral becomes (ρ*d*ρ*d*φ dz).
(See our atom on "Double integral in polar coordinates.
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### Examples

1.
The region is *z* component is unvaried during the transformation, the *dx dy dz* differentials vary as in the passage in polar coordinates: therefore, they become *ρ dρ dφ dz*.
Finally, it is possible to apply the final formula to cylindrical coordinates: *z* interval and even transform the circular base and the function.

2. The function *D* in cylindrical coordinates is the following: