# triangle_lyness_rule

triangle_lyness_rule, a MATLAB code which produces the Lyness-Jespersen family of quadrature rules over the interior of a triangle in 2D.

The rules have the following orders (number of points) and precisions (maximum degree of polynomials whose integrals they can compute exactly):
RuleOrderPrecision
0 1 1
1 3 2
2 4 2
3 4 3
4 7 3
5 6 4
6 10 4
7 9 4
8 7 5
9 10 5
10 12 6
11 16 6
12 13 6
13 13 7
14 16 7
15 16 8
16 21 8
17 16 8
18 19 9
19 22 9
20 2711
21 2811

### Languages:

triangle_lyness_rule is available in a C++ version and a FORTRAN90 version and a MATLAB version.

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### Reference:

1. James Lyness, Dennis Jespersen,
Moderate Degree Symmetric Quadrature Rules for the Triangle,
Journal of the Institute of Mathematics and its Applications,
Volume 15, Number 1, February 1975, pages 19-32.

### Source Code:

Last revised on 06 April 2019.