.TH "SRC/dlaed0.f" 3 "Version 3.12.0" "LAPACK" \" -*- nroff -*-
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.SH NAME
SRC/dlaed0.f
.SH SYNOPSIS
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.SS "Functions/Subroutines"

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.RI "subroutine \fBdlaed0\fP (icompq, qsiz, n, d, e, q, ldq, qstore, ldqs, work, iwork, info)"
.br
.RI "\fBDLAED0\fP used by DSTEDC\&. Computes all eigenvalues and corresponding eigenvectors of an unreduced symmetric tridiagonal matrix using the divide and conquer method\&. "
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.SH "Function/Subroutine Documentation"
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.SS "subroutine dlaed0 (integer icompq, integer qsiz, integer n, double precision, dimension( * ) d, double precision, dimension( * ) e, double precision, dimension( ldq, * ) q, integer ldq, double precision, dimension( ldqs, * ) qstore, integer ldqs, double precision, dimension( * ) work, integer, dimension( * ) iwork, integer info)"

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\fBDLAED0\fP used by DSTEDC\&. Computes all eigenvalues and corresponding eigenvectors of an unreduced symmetric tridiagonal matrix using the divide and conquer method\&.  
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\fBPurpose:\fP
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.nf
!>
!> DLAED0 computes all eigenvalues and corresponding eigenvectors of a
!> symmetric tridiagonal matrix using the divide and conquer method\&.
!> 
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.RE
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\fBParameters\fP
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\fIICOMPQ\fP 
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!>          ICOMPQ is INTEGER
!>          = 0:  Compute eigenvalues only\&.
!>          = 1:  Compute eigenvectors of original dense symmetric matrix
!>                also\&.  On entry, Q contains the orthogonal matrix used
!>                to reduce the original matrix to tridiagonal form\&.
!>          = 2:  Compute eigenvalues and eigenvectors of tridiagonal
!>                matrix\&.
!> 
.fi
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\fIQSIZ\fP 
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!>          QSIZ is INTEGER
!>         The dimension of the orthogonal matrix used to reduce
!>         the full matrix to tridiagonal form\&.  QSIZ >= N if ICOMPQ = 1\&.
!> 
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\fIN\fP 
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!>          N is INTEGER
!>         The dimension of the symmetric tridiagonal matrix\&.  N >= 0\&.
!> 
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\fID\fP 
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!>          D is DOUBLE PRECISION array, dimension (N)
!>         On entry, the main diagonal of the tridiagonal matrix\&.
!>         On exit, its eigenvalues\&.
!> 
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\fIE\fP 
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!>          E is DOUBLE PRECISION array, dimension (N-1)
!>         The off-diagonal elements of the tridiagonal matrix\&.
!>         On exit, E has been destroyed\&.
!> 
.fi
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\fIQ\fP 
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!>          Q is DOUBLE PRECISION array, dimension (LDQ, N)
!>         On entry, Q must contain an N-by-N orthogonal matrix\&.
!>         If ICOMPQ = 0    Q is not referenced\&.
!>         If ICOMPQ = 1    On entry, Q is a subset of the columns of the
!>                          orthogonal matrix used to reduce the full
!>                          matrix to tridiagonal form corresponding to
!>                          the subset of the full matrix which is being
!>                          decomposed at this time\&.
!>         If ICOMPQ = 2    On entry, Q will be the identity matrix\&.
!>                          On exit, Q contains the eigenvectors of the
!>                          tridiagonal matrix\&.
!> 
.fi
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\fILDQ\fP 
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!>          LDQ is INTEGER
!>         The leading dimension of the array Q\&.  If eigenvectors are
!>         desired, then  LDQ >= max(1,N)\&.  In any case,  LDQ >= 1\&.
!> 
.fi
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\fIQSTORE\fP 
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!>          QSTORE is DOUBLE PRECISION array, dimension (LDQS, N)
!>         Referenced only when ICOMPQ = 1\&.  Used to store parts of
!>         the eigenvector matrix when the updating matrix multiplies
!>         take place\&.
!> 
.fi
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\fILDQS\fP 
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!>          LDQS is INTEGER
!>         The leading dimension of the array QSTORE\&.  If ICOMPQ = 1,
!>         then  LDQS >= max(1,N)\&.  In any case,  LDQS >= 1\&.
!> 
.fi
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\fIWORK\fP 
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!>          WORK is DOUBLE PRECISION array,
!>         If ICOMPQ = 0 or 1, the dimension of WORK must be at least
!>                     1 + 3*N + 2*N*lg N + 3*N**2
!>                     ( lg( N ) = smallest integer k
!>                                 such that 2^k >= N )
!>         If ICOMPQ = 2, the dimension of WORK must be at least
!>                     4*N + N**2\&.
!> 
.fi
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\fIIWORK\fP 
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!>          IWORK is INTEGER array,
!>         If ICOMPQ = 0 or 1, the dimension of IWORK must be at least
!>                        6 + 6*N + 5*N*lg N\&.
!>                        ( lg( N ) = smallest integer k
!>                                    such that 2^k >= N )
!>         If ICOMPQ = 2, the dimension of IWORK must be at least
!>                        3 + 5*N\&.
!> 
.fi
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\fIINFO\fP 
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!>          INFO is INTEGER
!>          = 0:  successful exit\&.
!>          < 0:  if INFO = -i, the i-th argument had an illegal value\&.
!>          > 0:  The algorithm failed to compute an eigenvalue while
!>                working on the submatrix lying in rows and columns
!>                INFO/(N+1) through mod(INFO,N+1)\&.
!> 
.fi
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.RE
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\fBAuthor\fP
.RS 4
Univ\&. of Tennessee 

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Univ\&. of California Berkeley 

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Univ\&. of Colorado Denver 

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NAG Ltd\&. 
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\fBContributors:\fP
.RS 4
Jeff Rutter, Computer Science Division, University of California at Berkeley, USA 
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Definition at line \fB170\fP of file \fBdlaed0\&.f\fP\&.
.SH "Author"
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Generated automatically by Doxygen for LAPACK from the source code\&.