<a name="453"></a><a name="page208"></a>SUBROUTINE SBDSDC( UPLO, COMPQ, N, D, E, U, LDU, VT, LDVT, Q, IQ,$                    WORK, IWORK, INFO )CHARACTER          COMPQ,  UPLOINTEGER            INFO, LDU, LDVT, NINTEGER            IQ ( * ), IWORK ( * )REAL               D ( * ), E ( * ), Q ( * ), U (LDU, * ),$                    VT ( LDVT, * ), WORK ( * )

Purpose

SBDSDC computes the singular value decomposition (SVD) of a real n-by-n (upper or lower) bidiagonal matrix B: B = U*S*VT, using a divide and conquer method, where S is a diagonal matrix with non-negative diagonal elements (the singular values of B), and U and VT are orthogonal matrices of left and right singular vectors, respectively. SBDSDC can be used to compute all singular values, and optionally, singular vectors or singular vectors in compact form.

This code makes very mild assumptions about floating point arithmetic. It will work on machines with a guard digit in add/subtract, or on those binary machines without guard digits which subtract like...