Computes selected eigenvalues of a real symmetric tridiagonal matrix by bisection.
The routine computes some (or all) of the eigenvalues of a real symmetric tridiagonal matrix
Tby bisection. The routine searches for zero or negligible off-diagonal elements to see if
Tsplits into block-diagonal form
. Then it performs bisection on each of the blocks
and returns the block index of each computed eigenvalue, so that a subsequent call to stein can also take advantage of the block structure.
See also laebz.
- Must beCHARACTER*1.'A'or'V'or'I'.If, the routine computes all eigenvalues.range='A'If, the routine computes eigenvaluesrange='V'w(in the half-open interval:i).vl<w(i)≤vuIf, the routine computes eigenvalues with indicesrange='I'iltoiu.
- Must beCHARACTER*1.'B'or'E'.If, the eigenvalues are to be ordered from smallest to largest within each split-off block.order='B'If, the eigenvalues for the entire matrix are to be ordered from smallest to largest.order='E'
- The order of the matrixINTEGER.T().n≥0
- REALforsstebzDOUBLE PRECISIONfordstebz.Ifrange='V'