tetrahedron_witherden_rule, a Fortran90 code which returns a symmetric Witherden quadrature rule for the tetrahedron, with exactness up to total degree 10.
The data is given for the tetrahedron: with vertices (0,0,0), (1,0,0), (0,1,0), (0,0,1).
We suppose we are given a tetrahedron T with vertices A, B, C, D. We call a rule with n points, returning barycentric coordinates a, b, c, d, and weights w. Then the integral I of f(x,y,z) over T is approximated by Q as follows:
(x,y,z) = a(1:n) * A + b(1:n) * B + c(1:n) * C + d(1:n) * D
Q = volume(T) * sum ( 1 <= i <= n ) w(i) * f(x(i),y(i),z(i))
The computer code and data files made available on this web page are distributed under the MIT license
tetrahedron_witherden_rule is available in a C version and a C++ version and a Fortran90 version and a MATLAB version and an Octave versionand a Python version.
tetrahedron_witherden_rule_test
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