SLAEDA(3)

📦 version 3.12.0, in opensuse-leap 16.0

🌸 SLAEDA(3) — Library Functions Manual 🌸

okay so bestie, this is the manual page for SLAEDA(3), and the source file is literally:

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

No cap, that’s the whole path. 💅

📛 NAME

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

Yes, the NAME section is just the file path. Iconic. ✨

🛰️ SYNOPSIS

✨ Functions/Subroutines ✨

subroutine SLAEDA (n, tlvls, curlvl, curpbm, prmptr, perm, givptr,
    givcol, givnum, q, qptr, z, ztemp, info)

SLAEDA used by SSTEDC. Computes the Z vector determining the rank-one modification of the diagonal matrix. Used when the original matrix is dense.

🔥 Function/Subroutine Documentation 🔥

subroutine SLAEDA (integer n, integer tlvls, integer curlvl, integer curpbm,
    integer, dimension( * ) prmptr, integer, dimension( * ) perm, integer,
    dimension( * ) givptr, integer, dimension( 2, * ) givcol, real,
    dimension( 2, * ) givnum, real, dimension( * ) q, integer, dimension( *
    ) qptr, real, dimension( * ) z, real, dimension( * ) ztemp, integer
    info)

SLAEDA used by SSTEDC. Computes the Z vector determining the rank-one modification of the diagonal matrix. Used when the original matrix is dense.

🎯 Purpose

SLAEDA computes the Z vector corresponding to the merge step in the CURLVLth step of the merge process with TLVLS steps for the CURPBMth problem.

🧸 Parameters

N

N is INTEGER. The dimension of the symmetric tridiagonal matrix. N >= 0.

TLVLS

TLVLS is INTEGER. The total number of merging levels in the overall divide and conquer tree.

CURLVL

CURLVL is INTEGER. The current level in the overall merge routine, 0 <= curlvl <= tlvls.

CURPBM

CURPBM is INTEGER. The current problem in the current level in the overall merge routine (counting from upper left to lower right).

PRMPTR

PRMPTR is INTEGER array, dimension (N lg N). Contains a list of pointers which indicate where in PERM a level’s permutation is stored. PRMPTR(i+1) - PRMPTR(i) indicates the size of the permutation and incidentally the size of the full, non-deflated problem.

PERM

PERM is INTEGER array, dimension (N lg N). Contains the permutations (from deflation and sorting) to be applied to each eigenblock.

GIVPTR

GIVPTR is INTEGER array, dimension (N lg N). Contains a list of pointers which indicate where in GIVCOL a level’s Givens rotations are stored. GIVPTR(i+1) - GIVPTR(i) indicates the number of Givens rotations.

GIVCOL

GIVCOL is INTEGER array, dimension (2, N lg N). Each pair of numbers indicates a pair of columns to take place in a Givens rotation.

GIVNUM

GIVNUM is REAL array, dimension (2, N lg N). Each number indicates the S value to be used in the corresponding Givens rotation.

Q

Q is REAL array, dimension (N**2). Contains the square eigenblocks from previous levels, the starting positions for blocks are given by QPTR.

QPTR

QPTR is INTEGER array, dimension (N+2). Contains a list of pointers which indicate where in Q an eigenblock is stored. SQRT( QPTR(i+1) - QPTR(i) ) indicates the size of the block.

Z

Z is REAL array, dimension (N). On output this vector contains the updating vector (the last row of the first sub-eigenvector matrix and the first row of the second sub-eigenvector matrix).

ZTEMP

ZTEMP is REAL array, dimension (N).

INFO

INFO is INTEGER.

  • = 0: successful exit.
  • < 0: if INFO = -i, the i-th argument had an illegal value.

🧑‍🎓 Author

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

🫶 Contributors

Jeff Rutter, Computer Science Division, University of California at Berkeley, USA

Definition at line 164 of file slaeda.f.

📝 Author

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LAPACK Version 3.12.0 — footer path: /home/abui...RC/slaeda.f(3). Date? Not listed on the page, so I’m not inventing one. That’s the whole manual page, bestie. 💖✨🎀

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