SRC/dspcon.f(3)

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version 3.12.1 · 7 versions
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🩷 SRC/dspcon.f 🩷

okay bestie, welcome to the Library Functions Manual page for SRC/dspcon.f 💅 this is the whole DSPCON situation, and we are keeping every single detail. periodt.

📛 NAME

SRC/dspcon.f

📚 SYNOPSIS

🧩 Functions/Subroutines

subroutine dspcon (uplo, n, ap, ipiv, anorm, rcond, work, iwork, info)
    DSPCON

🛠️ Function/Subroutine Documentation

subroutine dspcon (character uplo, integer n, double precision, dimension( *
) ap, integer, dimension( * ) ipiv, double precision anorm, double
precision rcond, double precision, dimension( * ) work, integer,
dimension( * ) iwork, integer info)
    DSPCON

🎯 Purpose

okay so DSPCON estimates the reciprocal of the condition number (in the 1-norm) of a real symmetric packed matrix A using the factorization A = U*D*U**T or A = L*D*L**T computed by DSPTRF ✨ 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))). that's the whole purpose, no cap 💖

🧾 Parameters

  • UPLO — UPLO is CHARACTER*1 and it specifies whether the details of the factorization are stored as an upper or lower triangular matrix. = 'U': upper triangular, form is A = U*D*U**T; = 'L': lower triangular, form is A = L*D*L**T.
  • N — N is INTEGER, the order of the matrix A. N >= 0.
  • AP — AP is DOUBLE PRECISION array, dimension (N*(N+1)/2). it's the block diagonal matrix D and the multipliers used to obtain the factor U or L as computed by DSPTRF, stored as a packed triangular matrix 🎀
  • IPIV — IPIV is INTEGER array, dimension (N). details of the interchanges and the block structure of D as determined by DSPTRF.
  • ANORM — ANORM is DOUBLE PRECISION. the 1-norm of the original matrix A.
  • RCOND — RCOND is DOUBLE PRECISION. 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 DOUBLE PRECISION array, dimension (2*N).
  • IWORK — IWORK is INTEGER 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.

Definition at line 123 of file dspcon.f.

🤖 Author

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xoxo bestie, this was LAPACK Version 3.12.0 💖 source/page: SRC/dspcon.f(3) 🫶

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