SRC/sppcon.f(3)

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💖 SRC/sppcon.f 💖

okay so this is the SRC/sppcon.f page from the Library Functions Manual — manual name folded in near the top like a little bow 🎀. It’s giving “LAPACK function documentation but make it cute,” and we’re keeping every detail, no cap 💅.

🌸 NAME 🌸

SRC/sppcon.f

✨ SYNOPSIS ✨

💫 Functions/Subroutines 💫

subroutine sppcon (uplo, n, ap, anorm, rcond, work, iwork, info)
    SPPCON

🌟 Function/Subroutine Documentation 🌟

subroutine sppcon (character uplo, integer n, real, dimension( * ) ap, real anorm, real rcond, real, dimension( * ) work, integer, dimension( * ) iwork, integer info)
    SPPCON

🦋 Purpose 🦋

SPPCON estimates the reciprocal of the condition number (in the 1-norm) of a real symmetric positive definite packed matrix using the Cholesky factorization A = U**T*U or A = L*L**T computed by SPPTRF.

An estimate is obtained for norm(inv(A)), and the reciprocal of the condition number is computed as RCOND = 1 / (ANORM * norm(inv(A))).

🎀 Parameters 🎀

  • UPLO — UPLO is CHARACTER*1; = 'U': Upper triangle of A is stored; = 'L': Lower triangle of A is stored.
  • N — N is INTEGER; The order of the matrix A. N >= 0.
  • AP — AP is REAL array, dimension (N*(N+1)/2); The triangular factor U or L from the Cholesky factorization A = U**T*U or A = L*L**T, packed columnwise in a linear array. The j-th column of U or L is stored in the array AP as follows: if UPLO = 'U', AP(i + (j-1)*j/2) = U(i,j) for 1<=i<=j; if UPLO = 'L', AP(i + (j-1)*(2n-j)/2) = L(i,j) for j<=i<=n.
  • ANORM — ANORM is REAL; The 1-norm (or infinity-norm) of the symmetric matrix A.
  • RCOND — RCOND is REAL; 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 REAL array, dimension (3*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 117 of file sppcon.f.

🌈 Author (the auto-generated one) 🌈

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