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Ansatz (Ger., "onset"; today, "approach, setup, starting point"; plural: Ansätze) is a German noun with several meanings in the English language.[1] The term "Ansatz" is used in describing solution methods for differential equations.

Contents

Definition

More formally, in physics and mathematics, an Ansatz is an educated guess[2] that is verified later by its results. An Ansatz is the establishment of the starting equation(s) describing a mathematical or physical problem. It can take into consideration boundary conditions. After an Ansatz has been established, the equations are solved for the general function of interest. Typically, a word problem starts by writing down the Ansatz with subsequent refinement leading to the solution of the problem.

Examples

Given a set of experimental data that looks to be clustered about a line, a linear ansatz could be made to find the parameters of the line by a least squares curve fit. Variational approximation methods use ansätze and then fit the parameters.

Another example could be the mass, energy, and entropy balance equations that, considered simultaneous for purposes of the elementary operations of linear algebra, are the ansatz to most basic problems of thermodynamics.

Another example of ansatz is to suppose the solutions of a homogeneous linear differential equation and difference equation to have, respectively, exponential and power form. More generally one can guess a particular solution of a system of equations and test such an ansatz by direct substitution of the solution in the system of equations.

See also

Notes

  1. ^ Various interpretations of Ansatz include the "lengthening piece" or "mouthpiece" of a musical instrument, the "onset" or "start" of something, a "disposition", an "arrangement" (as in arithmetic, calculation, etc.), and so on. Schöffler-Weiss 1968, Part II German-English, p.15
  2. ^ In his book on "The Nature of Mathematical Modelling", Neil Gershenfeld introduces Ansatz, with interpretation "a trial answer", to be an important technique for solving differential equations. Gershenfeld 1999, p.10.

References

  1. Gershenfeld, Neil A. (1999), The Nature of mathematical Modeling, Cambridge University Press, ISBN 0 521 57095 6  
  2. Weis, Dr. Erich; Dr. Heinrich Mattutat (1968), The New Schöffler-Weis Compact German and English Dictionary, Ernst Klett Verlag, Stuttgart, ISBN 0 245 59813 8  
  3. Karbach, M.; Müller, G. (September 10 1998) (PDF), Introduction to the Bethe ansatz I. Computers in Physics 11 (1997), 36-43., http://www.phys.uri.edu/~gerhard/MSS/ms82.pdf, retrieved 2008-10-25  
  4. Karbach, M.; Hu, K.; Müller, G. (September 10 1998) (PDF), Introduction to the Bethe ansatz II. Computers in Physics 12 (1998), 565-573., http://www.phys.uri.edu/~gerhard/MSS/ms86.pdf, retrieved 2008-10-25  
  5. Karbach, M.; Hu, K.; Müller, G. (August 1 2000) (PDF), Introduction to the Bethe ansatz III., http://www.phys.uri.edu/~gerhard/MSS/ms91.pdf, retrieved 2008-10-25  

Wiktionary

Up to date as of January 14, 2010

Definition from Wiktionary, a free dictionary

Contents

German

Pronunciation

  • IPA: /ˈanzats/

Noun

Ansatz m. (genitive Ansatzes, plural Ansätze)

  1. approach
  2. ansatz (a mathematical expression assumed to describe a certain phenomenon, but without a proved justification for its use. It often is related to empirically obtained formulae).
  3. attempt

Declension








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