.TH "sterf" 3 "Wed Feb 7 2024 11:30:40" "Version 3.12.0" "LAPACK" \" -*- nroff -*-
.ad l
.nh
.SH NAME
sterf \- sterf: eig, QR iteration
.SH SYNOPSIS
.br
.PP
.SS "Functions"

.in +1c
.ti -1c
.RI "subroutine \fBdsterf\fP (n, d, e, info)"
.br
.RI "\fBDSTERF\fP "
.ti -1c
.RI "subroutine \fBssterf\fP (n, d, e, info)"
.br
.RI "\fBSSTERF\fP "
.in -1c
.SH "Detailed Description"
.PP 

.SH "Function Documentation"
.PP 
.SS "subroutine dsterf (integer n, double precision, dimension( * ) d, double precision, dimension( * ) e, integer info)"

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

.PP
.nf
 DSTERF computes all eigenvalues of a symmetric tridiagonal matrix
 using the Pal-Walker-Kahan variant of the QL or QR algorithm\&.
.fi
.PP
 
.RE
.PP
\fBParameters\fP
.RS 4
\fIN\fP 
.PP
.nf
          N is INTEGER
          The order of the matrix\&.  N >= 0\&.
.fi
.PP
.br
\fID\fP 
.PP
.nf
          D is DOUBLE PRECISION array, dimension (N)
          On entry, the n diagonal elements of the tridiagonal matrix\&.
          On exit, if INFO = 0, the eigenvalues in ascending order\&.
.fi
.PP
.br
\fIE\fP 
.PP
.nf
          E is DOUBLE PRECISION array, dimension (N-1)
          On entry, the (n-1) subdiagonal elements of the tridiagonal
          matrix\&.
          On exit, E has been destroyed\&.
.fi
.PP
.br
\fIINFO\fP 
.PP
.nf
          INFO is INTEGER
          = 0:  successful exit
          < 0:  if INFO = -i, the i-th argument had an illegal value
          > 0:  the algorithm failed to find all of the eigenvalues in
                a total of 30*N iterations; if INFO = i, then i
                elements of E have not converged to zero\&.
.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

.SS "subroutine ssterf (integer n, real, dimension( * ) d, real, dimension( * ) e, integer info)"

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

.PP
.nf
 SSTERF computes all eigenvalues of a symmetric tridiagonal matrix
 using the Pal-Walker-Kahan variant of the QL or QR algorithm\&.
.fi
.PP
 
.RE
.PP
\fBParameters\fP
.RS 4
\fIN\fP 
.PP
.nf
          N is INTEGER
          The order of the matrix\&.  N >= 0\&.
.fi
.PP
.br
\fID\fP 
.PP
.nf
          D is REAL array, dimension (N)
          On entry, the n diagonal elements of the tridiagonal matrix\&.
          On exit, if INFO = 0, the eigenvalues in ascending order\&.
.fi
.PP
.br
\fIE\fP 
.PP
.nf
          E is REAL array, dimension (N-1)
          On entry, the (n-1) subdiagonal elements of the tridiagonal
          matrix\&.
          On exit, E has been destroyed\&.
.fi
.PP
.br
\fIINFO\fP 
.PP
.nf
          INFO is INTEGER
          = 0:  successful exit
          < 0:  if INFO = -i, the i-th argument had an illegal value
          > 0:  the algorithm failed to find all of the eigenvalues in
                a total of 30*N iterations; if INFO = i, then i
                elements of E have not converged to zero\&.
.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

.SH "Author"
.PP 
Generated automatically by Doxygen for LAPACK from the source code\&.