laed5

slaed5

Functions

void slaed5(
    const INT           i,
    const f32* restrict D,
    const f32* restrict Z,
          f32* restrict delta,
    const f32           rho,
          f32*          dlam
);

void slaed5(const INT i, const f32 *restrict D, const f32 *restrict Z, f32 *restrict delta, const f32 rho, f32 *dlam)

SLAED5 computes the I-th eigenvalue of a symmetric rank-one modification of a 2-by-2 diagonal matrix.

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

The diagonal elements in the array D are assumed to satisfy D(0) < D(1).

We also assume RHO > 0 and that the Euclidean norm of the vector Z is one.

Parameters

in

i

The index of the eigenvalue to be computed. i = 0 or i = 1.

in

D

Double precision array, dimension (2). The original eigenvalues. We assume D[0] < D[1].

in

Z

Double precision array, dimension (2). The components of the updating vector.

out

delta

Double precision array, dimension (2). The vector DELTA contains the information necessary to construct the eigenvectors.

in

rho

The scalar in the symmetric updating formula.

out

dlam

The computed lambda_I, the I-th updated eigenvalue.

dlaed5

Functions

void dlaed5(
    const INT           i,
    const f64* restrict D,
    const f64* restrict Z,
          f64* restrict delta,
    const f64           rho,
          f64*          dlam
);

void dlaed5(const INT i, const f64 *restrict D, const f64 *restrict Z, f64 *restrict delta, const f64 rho, f64 *dlam)

DLAED5 computes the I-th eigenvalue of a symmetric rank-one modification of a 2-by-2 diagonal matrix.

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

The diagonal elements in the array D are assumed to satisfy D(0) < D(1).

We also assume RHO > 0 and that the Euclidean norm of the vector Z is one.

Parameters

in

i

The index of the eigenvalue to be computed. i = 0 or i = 1.

in

D

Double precision array, dimension (2). The original eigenvalues. We assume D[0] < D[1].

in

Z

Double precision array, dimension (2). The components of the updating vector.

out

delta

Double precision array, dimension (2). The vector DELTA contains the information necessary to construct the eigenvectors.

in

rho

The scalar in the symmetric updating formula.

out

dlam

The computed lambda_I, the I-th updated eigenvalue.