In numerical analysis, the balancing domain decomposition method (BDD) is an iterative method to find the solution of a symmetric positive definite system of linear algebraic equations arising from the finite element method.
 In each iteration, it combines the solution of local problems on non-overlapping subdomains with a coarse problem created from the subdomain nullspaces.
 BDD requires only solution of subdomain problems rather than access to the matrices of those problems, so it is applicable to situations where only the solution operators are available, such as in oil reservoir simulation by mixed finite elements.
 In its original formulation, BDD performs well only for 2nd order problems, such elasticity in 2D and 3D.
 For 4th order problems, such as plate bending, it needs to be modified by adding to the coarse problem special basis functions that enforce continuity of the solution at subdomain corners, which makes it however more expensive.
 The BDDC method uses the same corner basis functions as, but in an additive rather than multiplicative fashion.
 The dual counterpart to BDD is FETI, which enforces the equality of the solution between the subdomain by Lagrange multipliers.
 The base versions of BDD and FETI are not mathematically equivalent, though a special version of FETI designed to be robust for hard problems has the same eigenvalues and thus essentially the same performance as BDD.
Christian Vater (born November 15, 1974) is the founder of the independent German charitable foundation "Deutschland rundet auf" ("Germany rounds up").
 Born in Berlin, Vater is a social entrepreneur since 2009.
 Previously, he worked as a music manager.
Solution selling is a sales methodology.
 Rather than just promoting an existing product, the salesperson focuses on the customer's problems and addresses the issue with appropriate offerings (product and services).
 The problem resolution is what constitutes a "solution".
 Solution selling is usually used in sales situations where products are just one of the elements that lead to a solution.
 Often the real solution develops after the sales process - as with software or large plant engineering and construction projects.
 It is typical for solution selling situations that the buyer only rarely purchases such a solution and instead needs the knowledge of the solution partner.
Social conservatism in the United States is a political ideology focused on the preservation of traditional values and beliefs, hearkening back to values believed to be present at the American founding.
 It focuses on a concern with moral and social values which proponents of the ideology see as degraded in modern society by social democracy and liberalism.
 Social conservatism, while defined differently by many scholars, is often conflated with the Christian right.
 Religious conservatives push for a focus on Judeo-Christian traditions as a guiding force for the country on social issues, leading them to be considered social conservatives.
 Social conservatives are concerned with many social issues such as abortion, sex education, gun control, the equal rights amendment, school prayer, same-sex marriage, and many others.
 They oppose many of the cultural changes brought on by the culture wars and the sexual revolution.
 Summarily, this branch of conservatism is concerned with moral and social issues within the United States and uses tradition, strict morals, and religion as solutions for these problems.
Social entrepreneurship is the use of the techniques by start up companies and other entrepreneurs to develop, fund and implement solutions to social, cultural, or environmental issues.
 This concept may be applied to a variety of organizations with different sizes, aims, and beliefs.
 For-profit entrepreneurs typically measure performance using business metrics like profit, revenues and increases in stock prices, but social entrepreneurs are either non-profits or blend for-profit goals with generating a positive "return to society" and therefore must use different metrics.
 Social entrepreneurship typically attempts to further broad social, cultural, and environmental goals often associated with the voluntary sector in areas such as poverty alleviation, health care and community development.
The finite water-content vadose zone flux method represents a one-dimensional alternative to the numerical solution of Richards' equation for simulating the movement of water in unsaturated soils.
 The finite water-content method is an ordinary differential equation alternative to the Richards partial differential equation.
 The Richards equation is difficult to approximate in general because it does not have a closed-form analytical solution except in a few cases.
 The finite water-content method, is perhaps the first generic replacement for the numerical solution of the Richards' equation.
 The finite water-content solution has several advantages over the Richards equation solution.
 First, as an ordinary differential equation it is explicit, guaranteed to converge and computationally inexpensive to solve.
 Second, using a finite volume solution methodology it is guaranteed to conserve mass.
 The finite water content method readily simulates sharp wetting fronts, something that the Richards solution struggles with.
 The main limiting assumption required to use the finite water-content method is that the soil be homogeneous in layers.
The Journal of Social Issues is a quarterly peer-reviewed academic journal published by Wiley-Blackwell on behalf of the Society for the Psychological Study of Social Issues along with "Analyses of Social Issues and Public Policy" and "Social Issues and Policy Review".
 The journal was established in 1945.
 The current (2015) editor-in-chief is Ann Bettencourt (University of Missouri).
 The journal covers human and social issues such as poverty, privacy, youth violence, social class, and education.
Social Issues and Policy Review is an annual peer-reviewed academic journal published by Wiley-Blackwell on behalf of the Society for the Psychological Study of Social Issues along with "Analyses of Social Issues and Public Policy" and the "Journal of Social Issues".
 The journal was established in 2007.
 The current editors-in-chief are Samuel L. Gaertner (University of Delaware) and Rupert Brown (University of Sussex).
 The journal covers social issues and public policy.
Analyses of Social Issues and Public Policy is an annual peer-reviewed academic journal published by Wiley-Blackwell on behalf of the Society for the Psychological Study of Social Issues along with the "Journal of Social Issues" and "Social Issues and Policy Review".
 The journal was established in 2001.
 The current editor-in-chief is Kevin Lanning (Florida Atlantic University).
 The journal covers social psychological methods in the study of economic and social justice including ageism, heterosexism, racism, sexism, status quo bias, and other forms of discrimination, social problems such as climate change, extremism, homelessness, inter-group conflict, natural disasters, poverty, and terrorism, and social ideals such as democracy, empowerment, equality, health, and trust.
 Subscribers also receive a full subscription to the "Journal of Social Issues" and "Social Issues and Policy Review".
Christian Vater (11 October 1679 – 25 January 1756) was a German organ and harpsichord builder.

Question: Christian Vater is a practitioner of what method that develops and funds a solution to social issues?
Answer: Social entrepreneurship