# annulus_rule

annulus_rule, a C code which computes a quadrature rule over the interior of the annulus in 2D, with center (XC,YC), inner radius R1 and outer radius R2.

The user specifies values NT and NR, where NT is the number of equally spaced angles, and NR controls the number of radial points.

To use a rule that is equally powerful in R and T, typically, set NT = 4 * NR.

### Languages:

annulus_rule is available in a C version and a C++ version and a FORTRAN90 version and a MATLAB version and a Python version.

### Related Data and Programs:

annulus_monte_carlo a C code which uses the Monte Carlo method to estimate the integral of a function over the interior of a circular annulus in 2D.

circle_rule, a C code which computes quadrature rules over the circumference of a circle in 2D.

cube_arbq_rule, a C code which computes quadrature rules with exactness up to total degree 15, over the interior of a cube in 3D.

cube_felippa_rule, a C code which returns the points and weights of a Felippa quadrature rule over the interior of a cube in 3D.

disk_rule, a C code which computes quadrature rules over the interior of the general disk in 2D.

disk01_rule, a C code which computes quadrature rules over the interior of the unit disk in 2D.

pyramid_felippa_rule, a C code which returns Felippa's quadratures rules for approximating integrals over the interior of a pyramid in 3D.

pyramid_rule, a C code which computes a quadrature rule over the interior of the unit pyramid in 3D.

sphere_lebedev_rule, a C code which computes Lebedev quadrature rules on the surface of the unit sphere in 3D.

square_felippa_rule, a C code which returns the points and weights of a Felippa quadrature rule over the interior of a square in 2D.

tetrahedron_felippa_rule, a C code which returns Felippa's quadratures rules for approximating integrals over the interior of a tetrahedron in 3D.

triangle_felippa_rule, a C code which returns Felippa's quadratures rules for approximating integrals over the interior of a triangle in 2D.

wedge_felippa_rule, a C code which returns quadratures rules for approximating integrals over the interior of the unit wedge in 3D.

### Reference:

1. Philip Davis, Philip Rabinowitz,
Methods of Numerical Integration,
Second Edition,
Dover, 2007,
ISBN: 0486453391,
LC: QA299.3.D28.
2. Sylvan Elhay, Jaroslav Kautsky,
Algorithm 655: IQPACK, FORTRAN Subroutines for the Weights of Interpolatory Quadrature,
ACM Transactions on Mathematical Software,
Volume 13, Number 4, December 1987, pages 399-415.

### Source Code:

Last revised on 28 February 2022.