(S|D)LASV2¶

Single and double LASV2.

Description¶

Computes singular value decomposition for the 2x2 triangular matrix:

$\left[ \begin{matrix} \fvar{F} & \fvar{G} \\ 0 & \fvar{H} \\ \end{matrix} \right]$

The larger singular value is returned in SSMAX and the smaller in SSMIN. The left singular vector for SSMAX is (CSL, SNL) and the right singular vector for SSMAX is (CSR, SNR). On exit:

$\left[ \begin{matrix} \fvar{CSL} & \fvar{SNL} \\ -\fvar{SNL} & \fvar{CSL} \\ \end{matrix} \right] \mult \left[ \begin{matrix} \fvar{F} & \fvar{G} \\ 0 & \fvar{H} \\ \end{matrix} \right] \mult \left[ \begin{matrix} \fvar{CSR} & -\fvar{SNR} \\ \fvar{SNR} & \fvar{CSR} \\ \end{matrix} \right] = \left[ \begin{matrix} \fvar{SSMAX} & 0 \\ 0 & \fvar{SSMIN} \\ \end{matrix} \right]$

LAPACK Interface¶

void slasv2(const float *F, const float *G, const float *H, float *SSMIN,
    float *SSMAX, float *SNR, float *CSR, float *SNL, float *CSL);

void dlasv2(const double *F, const double *G, const double *H, double *SSMIN,
    double *SSMAX, double *SNR, double *CSR, double *SNL, double *CSL);

Arguments¶

F	Element of input matrix
G	Element of input matrix
H	Element of input matrix
SSMIN	Smallest singular value
SSMAX	Largest singular value
SNR	Second part of right singular vector
CSR	First part of right singular vector
SNL	Second part of left singular vector
CSL	First part of left singular vector