.TH "SRC/dlasd5.f" 3 "Version 3.12.0" "LAPACK" \" -*- nroff -*-
.ad l
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.SH NAME
SRC/dlasd5.f
.SH SYNOPSIS
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.PP
.SS "Functions/Subroutines"

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.RI "subroutine \fBdlasd5\fP (i, d, z, delta, rho, dsigma, work)"
.br
.RI "\fBDLASD5\fP computes the square root of the i-th eigenvalue of a positive symmetric rank-one modification of a 2-by-2 diagonal matrix\&. Used by sbdsdc\&. "
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.SH "Function/Subroutine Documentation"
.PP 
.SS "subroutine dlasd5 (integer i, double precision, dimension( 2 ) d, double precision, dimension( 2 ) z, double precision, dimension( 2 ) delta, double precision rho, double precision dsigma, double precision, dimension( 2 ) work)"

.PP
\fBDLASD5\fP computes the square root of the i-th eigenvalue of a positive symmetric rank-one modification of a 2-by-2 diagonal matrix\&. Used by sbdsdc\&.  
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\fBPurpose:\fP
.RS 4

.PP
.nf
 This subroutine computes the square root of the I-th eigenvalue
 of a positive symmetric rank-one modification of a 2-by-2 diagonal
 matrix

            diag( D ) * diag( D ) +  RHO * Z * transpose(Z) \&.

 The diagonal entries in the array D are assumed to satisfy

            0 <= D(i) < D(j)  for  i < j \&.

 We also assume RHO > 0 and that the Euclidean norm of the vector
 Z is one\&.
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.PP
 
.RE
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\fBParameters\fP
.RS 4
\fII\fP 
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          I is INTEGER
         The index of the eigenvalue to be computed\&.  I = 1 or I = 2\&.
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\fID\fP 
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          D is DOUBLE PRECISION array, dimension ( 2 )
         The original eigenvalues\&.  We assume 0 <= D(1) < D(2)\&.
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\fIZ\fP 
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          Z is DOUBLE PRECISION array, dimension ( 2 )
         The components of the updating vector\&.
.fi
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\fIDELTA\fP 
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          DELTA is DOUBLE PRECISION array, dimension ( 2 )
         Contains (D(j) - sigma_I) in its  j-th component\&.
         The vector DELTA contains the information necessary
         to construct the eigenvectors\&.
.fi
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\fIRHO\fP 
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          RHO is DOUBLE PRECISION
         The scalar in the symmetric updating formula\&.
.fi
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\fIDSIGMA\fP 
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          DSIGMA is DOUBLE PRECISION
         The computed sigma_I, the I-th updated eigenvalue\&.
.fi
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.br
\fIWORK\fP 
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          WORK is DOUBLE PRECISION array, dimension ( 2 )
         WORK contains (D(j) + sigma_I) in its  j-th component\&.
.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\&. 
.RE
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\fBContributors:\fP
.RS 4
Ren-Cang Li, Computer Science Division, University of California at Berkeley, USA 
.RE
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Definition at line \fB115\fP of file \fBdlasd5\&.f\fP\&.
.SH "Author"
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Generated automatically by Doxygen for LAPACK from the source code\&.