SPPCON(3)

💅 SPPCON(3) 💅

Library Functions Manual — okay bestie, we're in the Unix docs and this one is a LAPACK routine page. Buckle up, it's giving linear algebra but make it cute. 🦋

📛 NAME 📛

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

That's the source file this page is about. The subroutine itself is SPPCON, iykyk.

✨ SYNOPSIS ✨

🧚 Functions/Subroutines 🧚

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

💖 Function/Subroutine Documentation 💖

Here's the signature, bestie, in all its proper form:

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

🎯 Purpose 🎯

Okay so 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 — CHARACTER*1. = 'U': upper triangle of A is stored; = 'L': lower triangle of A is stored.
• N — INTEGER. The order of the matrix A. N >= 0.
• AP — REAL array, dimension (N*(N+1)/2). This is 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 — REAL. The 1-norm (or infinity-norm) of the symmetric matrix A.
• RCOND — 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 — REAL array, dimension (3*N).
• IWORK — INTEGER array, dimension (N).
• INFO — 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 🫶

Generated automatically by Doxygen for LAPACK from the source code.

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💖 Cute sign-off time: this page is from LAPACK, Version 3.12.0, with footer path /home/abui...RC/sppcon.f(3). The footer doesn't show a date field, so there's literally no date to quote — periodt. 🎀