.TH "TESTING/EIG/dbdt04.f" 3 "Version 3.12.0" "LAPACK" \" -*- nroff -*-
.ad l
.nh
.SH NAME
TESTING/EIG/dbdt04.f
.SH SYNOPSIS
.br
.PP
.SS "Functions/Subroutines"

.in +1c
.ti -1c
.RI "subroutine \fBdbdt04\fP (uplo, n, d, e, s, ns, u, ldu, vt, ldvt, work, resid)"
.br
.RI "\fBDBDT04\fP "
.in -1c
.SH "Function/Subroutine Documentation"
.PP 
.SS "subroutine dbdt04 (character uplo, integer n, double precision, dimension( * ) d, double precision, dimension( * ) e, double precision, dimension( * ) s, integer ns, double precision, dimension( ldu, * ) u, integer ldu, double precision, dimension( ldvt, * ) vt, integer ldvt, double precision, dimension( * ) work, double precision resid)"

.PP
\fBDBDT04\fP 
.PP
\fBPurpose:\fP
.RS 4

.PP
.nf
 DBDT04 reconstructs a bidiagonal matrix B from its (partial) SVD:
    S = U' * B * V
 where U and V are orthogonal matrices and S is diagonal\&.

 The test ratio to test the singular value decomposition is
    RESID = norm( S - U' * B * V ) / ( n * norm(B) * EPS )
 where VT = V' and EPS is the machine precision\&.
.fi
.PP
 
.RE
.PP
\fBParameters\fP
.RS 4
\fIUPLO\fP 
.PP
.nf
          UPLO is CHARACTER*1
          Specifies whether the matrix B is upper or lower bidiagonal\&.
          = 'U':  Upper bidiagonal
          = 'L':  Lower bidiagonal
.fi
.PP
.br
\fIN\fP 
.PP
.nf
          N is INTEGER
          The order of the matrix B\&.
.fi
.PP
.br
\fID\fP 
.PP
.nf
          D is DOUBLE PRECISION array, dimension (N)
          The n diagonal elements of the bidiagonal matrix B\&.
.fi
.PP
.br
\fIE\fP 
.PP
.nf
          E is DOUBLE PRECISION array, dimension (N-1)
          The (n-1) superdiagonal elements of the bidiagonal matrix B
          if UPLO = 'U', or the (n-1) subdiagonal elements of B if
          UPLO = 'L'\&.
.fi
.PP
.br
\fIS\fP 
.PP
.nf
          S is DOUBLE PRECISION array, dimension (NS)
          The singular values from the (partial) SVD of B, sorted in
          decreasing order\&.
.fi
.PP
.br
\fINS\fP 
.PP
.nf
          NS is INTEGER
          The number of singular values/vectors from the (partial)
          SVD of B\&.
.fi
.PP
.br
\fIU\fP 
.PP
.nf
          U is DOUBLE PRECISION array, dimension (LDU,NS)
          The n by ns orthogonal matrix U in S = U' * B * V\&.
.fi
.PP
.br
\fILDU\fP 
.PP
.nf
          LDU is INTEGER
          The leading dimension of the array U\&.  LDU >= max(1,N)
.fi
.PP
.br
\fIVT\fP 
.PP
.nf
          VT is DOUBLE PRECISION array, dimension (LDVT,N)
          The n by ns orthogonal matrix V in S = U' * B * V\&.
.fi
.PP
.br
\fILDVT\fP 
.PP
.nf
          LDVT is INTEGER
          The leading dimension of the array VT\&.
.fi
.PP
.br
\fIWORK\fP 
.PP
.nf
          WORK is DOUBLE PRECISION array, dimension (2*N)
.fi
.PP
.br
\fIRESID\fP 
.PP
.nf
          RESID is DOUBLE PRECISION
          The test ratio:  norm(S - U' * B * V) / ( n * norm(B) * EPS )
.fi
.PP
 
.RE
.PP
\fBAuthor\fP
.RS 4
Univ\&. of Tennessee 
.PP
Univ\&. of California Berkeley 
.PP
Univ\&. of Colorado Denver 
.PP
NAG Ltd\&. 
.RE
.PP

.PP
Definition at line \fB129\fP of file \fBdbdt04\&.f\fP\&.
.SH "Author"
.PP 
Generated automatically by Doxygen for LAPACK from the source code\&.