SRC/dsycon.f(3)

📦
version 3.12.1 · 4 versions
, in arch rolling

✨ NAME ✨

Bestie, this is the SRC/dsycon.f page from the Library Functions Manual — it's all about the DSYCON subroutine, and she is lowkey iconic. 💅

🌸 SYNOPSIS 🌸

🫶 Functions/Subroutines 🫶

  • subroutine dsycon (uplo, n, a, lda, ipiv, anorm, rcond, work, iwork, info) — DSYCON

💖 Function/Subroutine Documentation 💖

subroutine dsycon (character uplo, integer n, double precision, dimension(
    lda, * ) a, integer lda, integer, dimension( * ) ipiv, double precision
    anorm, double precision rcond, double precision, dimension( * ) work,
    integer, dimension( * ) iwork, integer info)

DSYCON

🦋 Purpose 🦋

Okay so DSYCON estimates the reciprocal of the condition number — in the 1-norm — of a real symmetric matrix A, using the factorization A = U*D*U**T or A = L*D*L**T computed by DSYTRF. Obsessed with her little factorization moment. ✨

An estimate is obtained for norm(inv(A)), and the reciprocal of the condition number is computed as:

RCOND = 1 / (ANORM * norm(inv(A)))

No cap, that formula is the whole vibe. 💖

🎀 Parameters 🎀

  • UPLO — UPLO is CHARACTER*1. It says whether the details of the factorization are stored as an upper or lower triangular matrix, bestie:
    • = 'U': Upper triangular, form is A = U*D*U**T;
    • = 'L': Lower triangular, form is A = L*D*L**T.
  • N — N is INTEGER. It's the order of the matrix A. And N >= 0, periodt. 💅
  • A — A is DOUBLE PRECISION array, dimension (LDA,N). This is the block diagonal matrix D and the multipliers used to obtain the factor U or L as computed by DSYTRF. She's giving factorization storage realness. 🦋
  • LDA — LDA is INTEGER. It's the leading dimension of the array A. So LDA >= max(1,N), fr fr. 🌸
  • IPIV — IPIV is INTEGER array, dimension (N). It holds the details of the interchanges and the block structure of D as determined by DSYTRF. Very iykyk. 👑
  • ANORM — ANORM is DOUBLE PRECISION. It's the 1-norm of the original matrix A. Simple, iconic, done. ⭐
  • RCOND — RCOND is DOUBLE PRECISION. It's the reciprocal of the condition number of the matrix A, computed as RCOND = 1/(ANORM * AINVNM), where AINVNM is an estimate of the 1-norm of inv(A) computed in this routine. The way that formula ate. 🔥
  • WORK — WORK is DOUBLE PRECISION array, dimension (2*N). That's the workspace, bestie. 🎀
  • IWORK — IWORK is INTEGER array, dimension (N). More workspace, but integer-flavored. 💜
  • 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.

Definition at line 128 of file dsycon.f.

🌈 Author 🌈

Generated automatically by Doxygen for LAPACK from the source code.

That's the whole page, bestie! This cutie is from LAPACK, Version 3.12.0, on the SRC/dsycon.f(3) page. Bye, love you! 💖🎀🦋

📦 where this page comes from