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

.in +1c
.ti -1c
.RI "subroutine \fBdsvdch\fP (n, s, e, svd, tol, info)"
.br
.RI "\fBDSVDCH\fP "
.in -1c
.SH "Function/Subroutine Documentation"
.PP 
.SS "subroutine dsvdch (integer n, double precision, dimension( * ) s, double precision, dimension( * ) e, double precision, dimension( * ) svd, double precision tol, integer info)"

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

.PP
.nf
 DSVDCH checks to see if SVD(1) ,\&.\&.\&., SVD(N) are accurate singular
 values of the bidiagonal matrix B with diagonal entries
 S(1) ,\&.\&.\&., S(N) and superdiagonal entries E(1) ,\&.\&.\&., E(N-1))\&.
 It does this by expanding each SVD(I) into an interval
 [SVD(I) * (1-EPS) , SVD(I) * (1+EPS)], merging overlapping intervals
 if any, and using Sturm sequences to count and verify whether each
 resulting interval has the correct number of singular values (using
 DSVDCT)\&. Here EPS=TOL*MAX(N/10,1)*MAZHEP, where MACHEP is the
 machine precision\&. The routine assumes the singular values are sorted
 with SVD(1) the largest and SVD(N) smallest\&.  If each interval
 contains the correct number of singular values, INFO = 0 is returned,
 otherwise INFO is the index of the first singular value in the first
 bad interval\&.
.fi
.PP
 
.RE
.PP
\fBParameters\fP
.RS 4
\fIN\fP 
.PP
.nf
          N is INTEGER
          The dimension of the bidiagonal matrix B\&.
.fi
.PP
.br
\fIS\fP 
.PP
.nf
          S is DOUBLE PRECISION array, dimension (N)
          The diagonal entries of the bidiagonal matrix B\&.
.fi
.PP
.br
\fIE\fP 
.PP
.nf
          E is DOUBLE PRECISION array, dimension (N-1)
          The superdiagonal entries of the bidiagonal matrix B\&.
.fi
.PP
.br
\fISVD\fP 
.PP
.nf
          SVD is DOUBLE PRECISION array, dimension (N)
          The computed singular values to be checked\&.
.fi
.PP
.br
\fITOL\fP 
.PP
.nf
          TOL is DOUBLE PRECISION
          Error tolerance for checking, a multiplier of the
          machine precision\&.
.fi
.PP
.br
\fIINFO\fP 
.PP
.nf
          INFO is INTEGER
          =0 if the singular values are all correct (to within
             1 +- TOL*MAZHEPS)
          >0 if the interval containing the INFO-th singular value
             contains the incorrect number of singular values\&.
.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 \fB96\fP of file \fBdsvdch\&.f\fP\&.
.SH "Author"
.PP 
Generated automatically by Doxygen for LAPACK from the source code\&.