SLAED5(3)

💖 SLAED5(3) 💖

okay so bestie, this is the SLAED5(3) page from the Library Functions Manual — the header title/path shows up as /home/abui...RC/slaed5.f(3), and it's giving “tiny LAPACK helper with main character energy.” ✨

🌸 NAME 🌸

/home/abuild/rpmbuild/BUILD/lapack-static-3.12.0-build/lapack-3.12.0/SRC/slaed5.f

🦋 SYNOPSIS 🦋

Functions/Subroutines

• subroutine SLAED5 (i, d, z, delta, rho, dlam) — SLAED5 used by SSTEDC. Solves the 2-by-2 secular equation.

🎀 Function/Subroutine Documentation 🎀

subroutine SLAED5 (integer i, real, dimension( 2 ) d, real, dimension( 2 )
       z, real, dimension( 2 ) delta, real rho, real dlam)

SLAED5 used by SSTEDC. Solves the 2-by-2 secular equation.

✨ Purpose ✨

This subroutine 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(i) < D(j)  for  i < j .

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

💖 Parameters 💖

• I — I is INTEGER. It's the index of the eigenvalue to be computed, bestie: I = 1 or I = 2.
• D — D is REAL array, dimension (2). The original eigenvalues. We assume D(1) < D(2).
• Z — Z is REAL array, dimension (2). The components of the updating vector.
• DELTA — DELTA is REAL array, dimension (2). The vector DELTA contains the information necessary to construct the eigenvectors.
• RHO — RHO is REAL. The scalar in the symmetric updating formula.
• DLAM — DLAM is REAL. The computed lambda_I, the I-th updated eigenvalue.

👑 Author 👑

• Univ. of Tennessee
• Univ. of California Berkeley
• Univ. of Colorado Denver
• NAG Ltd.

🌈 Contributors: 🌈

Ren-Cang Li, Computer Science Division, University of California at Berkeley, USA

Definition at line 107 of file slaed5.f.

🫶 Author 🫶

Generated automatically by Doxygen for LAPACK from the source code.

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mwah 💋 source/version sign-off: this is LAPACK, Version 3.12.0, with the footer path /home/abui...RC/slaed5.f(3). No date is shown in that footer, bestie, so I'm not making one up. 🫶