Class SturmCount
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- dev.nm.algebra.linear.matrix.doubles.factorization.eigen.mr3.SturmCount
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public class SturmCount extends Object
Computes the Sturm count, the number of negative pivots encountered while factoring tridiagonal T - σ I = LDLT. This implementation works directly on the factors without forming the tridiagonal matrix T. The Sturm count is also the number of eigenvalues of T less than σ.- See Also:
- "Marques, Osni A., Riedy E. Jason, and Vomel Christof, "LAPACK working note 172: Benefits of IEEE-754 features in modern symmetric tridiagonal eigensolvers", Technical Report UCB// CSD-05-1414, 2005."
- "Dhillon, Inderjit S. and Parlett, Beresford N., "Orthogonal eigenvectors and relative gaps", SIAM Journal on Matrix Analysis and Applications, 2004, Vol. 25, pp. 858-899."
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Constructor Summary
Constructors Constructor Description SturmCount(LDDecomposition LDLt, int twistIndex)
Creates an instance for computing the Sturm count of a given robust representation (T - σ I = LDLT).
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Constructor Detail
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SturmCount
public SturmCount(LDDecomposition LDLt, int twistIndex)
Creates an instance for computing the Sturm count of a given robust representation (T - σ I = LDLT).- Parameters:
LDLt
- the robust representation of TtwistIndex
- the twist index for the twisted factorization
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