SRC/chpcon.f(3)

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version 3.12.1 · 7 versions
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💖 SRC/chpcon.f 💖

Okay bestie, this page comes from the Library Functions Manual — it's giving C/Fortran linear algebra, and we're gonna get you through it. ✨

✨ NAME ✨

SRC/chpcon.f

🦋 SYNOPSIS 🦋

🧚 Functions/Subroutines 🧚

subroutine chpcon (uplo, n, ap, ipiv, anorm, rcond, work, info)
           CHPCON

🎀 Function/Subroutine Documentation 🎀

subroutine chpcon (character uplo, integer n, complex, dimension( * ) ap,
       integer, dimension( * ) ipiv, real anorm, real rcond, complex,
       dimension( * ) work, integer info)
       CHPCON

💅 Purpose

CHPCON estimates the reciprocal of the condition number of a complex Hermitian packed matrix A using the factorization A = U*D*U**H or A = L*D*L**H computed by CHPTRF.

An estimate is obtained for norm(inv(A)), and then the reciprocal of the condition number is computed as RCOND = 1 / (ANORM * norm(inv(A))). Math girlie behavior, honestly. 🧮✨

🔥 Parameters

  • UPLO — UPLO is CHARACTER*1. It specifies whether the details of the factorization are stored as an upper or lower triangular matrix. 'U' means upper triangular, form is A = U*D*U**H; 'L' means lower triangular, form is A = L*D*L**H. 👑
  • N — N is INTEGER. It's the order of the matrix A. Constraint: N >= 0. ✅
  • AP — AP is a COMPLEX array, dimension (N*(N+1)/2). It holds the block diagonal matrix D and the multipliers used to obtain the factor U or L as computed by CHPTRF, stored as a packed triangular matrix. 🎁
  • IPIV — IPIV is an INTEGER array, dimension (N). It has the details of the interchanges and the block structure of D as determined by CHPTRF. 🔁
  • ANORM — ANORM is REAL. It's the 1-norm of the original matrix A. 📏
  • RCOND — RCOND is REAL. 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. 🧮
  • WORK — WORK is a COMPLEX array, dimension (2*N). 🛠️
  • INFO — INFO is INTEGER. INFO = 0 means successful exit. INFO < 0 means 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 117 of file chpcon.f.

🌈 Author 🌈

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Footer sign-off time, bestie: LAPACK Version 3.12.0 — source SRC/chpcon.f(3). That's the footer energy, no date in sight 🙈. Go forth and condition those numbers. 💜🫶

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