Ansatz

Ansatz is a German language term often used by physicists and mathematicians. An ansatz is an assumed form for a mathematical function that is not based on any underlying theory or principle.

For example, 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 ansatzes and then fit the parameters.