Package org.apache.commons.math.linear
Interface LUDecomposition

 All Known Implementing Classes:
LUDecompositionImpl
public interface LUDecomposition
An interface to classes that implement an algorithm to calculate the LUdecomposition of a real matrix.The LUdecomposition of matrix A is a set of three matrices: P, L and U such that P×A = L×U. P is a rows permutation matrix that is used to rearrange the rows of A before so that it can be decomposed. L is a lower triangular matrix with unit diagonal terms and U is an upper triangular matrix.
This interface is based on the class with similar name from the JAMA library.
 a
getP
method has been added,  the
det
method has been renamed asgetDeterminant
,  the
getDoublePivot
method has been removed (but the int basedgetPivot
method has been kept),  the
solve
andisNonSingular
methods have been replaced by agetSolver
method and the equivalent methods provided by the returnedDecompositionSolver
.


Method Summary
All Methods Instance Methods Abstract Methods Modifier and Type Method Description double
getDeterminant()
Return the determinant of the matrixRealMatrix
getL()
Returns the matrix L of the decomposition.RealMatrix
getP()
Returns the P rows permutation matrix.int[]
getPivot()
Returns the pivot permutation vector.DecompositionSolver
getSolver()
Get a solver for finding the A × X = B solution in exact linear sense.RealMatrix
getU()
Returns the matrix U of the decomposition.



Method Detail

getL
RealMatrix getL()
Returns the matrix L of the decomposition.L is an lowertriangular matrix
 Returns:
 the L matrix (or null if decomposed matrix is singular)

getU
RealMatrix getU()
Returns the matrix U of the decomposition.U is an uppertriangular matrix
 Returns:
 the U matrix (or null if decomposed matrix is singular)

getP
RealMatrix getP()
Returns the P rows permutation matrix.P is a sparse matrix with exactly one element set to 1.0 in each row and each column, all other elements being set to 0.0.
The positions of the 1 elements are given by the
pivot permutation vector
. Returns:
 the P rows permutation matrix (or null if decomposed matrix is singular)
 See Also:
getPivot()

getPivot
int[] getPivot()
Returns the pivot permutation vector. Returns:
 the pivot permutation vector
 See Also:
getP()

getDeterminant
double getDeterminant()
Return the determinant of the matrix Returns:
 determinant of the matrix

getSolver
DecompositionSolver getSolver()
Get a solver for finding the A × X = B solution in exact linear sense. Returns:
 a solver

