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  2. Numerical methods for linear least squares - Wikipedia

    en.wikipedia.org/wiki/Numerical_methods_for...

    It can therefore be important that considerations of computation efficiency for such problems extend to all of the auxiliary quantities required for such analyses, and are not restricted to the formal solution of the linear least squares problem. Matrix calculations, like any other, are affected by rounding errors. An early summary of these ...

  3. Underdetermined system - Wikipedia

    en.wikipedia.org/wiki/Underdetermined_system

    If, on the other hand, the ranks of these two matrices are equal, the system must have at least one solution; since in an underdetermined system this rank is necessarily less than the number of unknowns, there are indeed an infinitude of solutions, with the general solution having k free parameters where k is the difference between the number ...

  4. Preconditioner - Wikipedia

    en.wikipedia.org/wiki/Preconditioner

    By analogy with linear systems, for an eigenvalue problem = one may be tempted to replace the matrix with the matrix using a preconditioner . However, this makes sense only if the seeking eigenvectors of A {\\displaystyle A} and P − 1 A {\\displaystyle P^{-1}A} are the same.

  5. Alternating-direction implicit method - Wikipedia

    en.wikipedia.org/wiki/Alternating-direction...

    In numerical linear algebra, the alternating-direction implicit (ADI) method is an iterative method used to solve Sylvester matrix equations.It is a popular method for solving the large matrix equations that arise in systems theory and control, [1] and can be formulated to construct solutions in a memory-efficient, factored form.

  6. Overdetermined system - Wikipedia

    en.wikipedia.org/wiki/Overdetermined_system

    For the system =, the least squares formula is obtained from the problem ‖ ‖, the solution of which can be written with the normal equations, [3] = (), where indicates a matrix transpose, provided exists (that is, provided A has full column rank). With this formula an approximate solution is found when no exact solution exists, and it gives ...

  7. Multigrid method - Wikipedia

    en.wikipedia.org/wiki/Multigrid_method

    The main idea of multigrid is to accelerate the convergence of a basic iterative method (known as relaxation, which generally reduces short-wavelength error) by a global correction of the fine grid solution approximation from time to time, accomplished by solving a coarse problem. The coarse problem, while cheaper to solve, is similar to the ...

  8. Numerical linear algebra - Wikipedia

    en.wikipedia.org/wiki/Numerical_linear_algebra

    For many problems in applied linear algebra, it is useful to adopt the perspective of a matrix as being a concatenation of column vectors. For example, when solving the linear system =, rather than understanding x as the product of with b, it is helpful to think of x as the vector of coefficients in the linear expansion of b in the basis formed by the columns of A.

  9. Matrix decomposition - Wikipedia

    en.wikipedia.org/wiki/Matrix_decomposition

    In the mathematical discipline of linear algebra, a matrix decomposition or matrix factorization is a factorization of a matrix into a product of matrices. There are many different matrix decompositions; each finds use among a particular class of problems.