DPPT01(3)

💅 DPPT01(3) — Library Functions Manual 💅

okay so bestie, welcome to DPPT01(3) in the Library Functions Manual. The header is giving truncated-path energy (/home/abui...IN/dppt01.f(3)), but the actual source file is the one below, and yes, it’s a whole LAPACK testing vibe. 🦋

---

🌸 NAME 🌸

/home/abuild/rpmbuild/BUILD/lapack-static-3.12.0-build/lapack-3.12.0/TESTING/LIN/dppt01.f

That’s the file, bestie. It’s the DPPT01 subroutine source page, and the manual page itself is DPPT01(3). 💖

✨ SYNOPSIS ✨

Functions/Subroutines

       subroutine DPPT01 (uplo, n, a, afac, rwork, resid)
           DPPT01

🦋 Function/Subroutine Documentation 🦋

Here’s the full signature, character-for-character, no cap:

   subroutine DPPT01 (character uplo, integer n, double precision, dimension( *
       ) a, double precision, dimension( * ) afac, double precision, dimension(
       * ) rwork, double precision resid)
       DPPT01

🎯 Purpose 🎯

Purpose tea: DPPT01 reconstructs a symmetric positive definite packed matrix A from its L*L' or U'*U factorization, then computes the residual. The exact glow-up is:

!>
!> DPPT01 reconstructs a symmetric positive definite packed matrix A
!> from its L*L' or U'*U factorization and computes the residual
!>    norm( L*L' - A ) / ( N * norm(A) * EPS ) or
!>    norm( U'*U - A ) / ( N * norm(A) * EPS ),
!> where EPS is the machine epsilon.
!>

🎀 Parameters 🎀

• UPLO — CHARACTER*1. Specifies whether the upper or lower triangular part of the symmetric matrix A is stored:
  • = 'U': Upper triangular
  • = 'L': Lower triangular
• N — INTEGER. The number of rows and columns of the matrix A. N >= 0.
• A — DOUBLE PRECISION array, dimension (N*(N+1)/2). The original symmetric matrix A, stored as a packed triangular matrix.
• AFAC — DOUBLE PRECISION array, dimension (N*(N+1)/2). On entry, the factor L or U from the L*L' or U'*U factorization of A, stored as a packed triangular matrix. It gets overwritten with the reconstructed matrix, and then with the difference L*L' - A (or U'*U - A).
• RWORK — DOUBLE PRECISION array, dimension (N).
• RESID — DOUBLE PRECISION.
  • If UPLO = 'L': norm(L*L' - A) / ( N * norm(A) * EPS )
  • If UPLO = 'U': norm(U'*U - A) / ( N * norm(A) * EPS )

👑 Author 👑

The academic icons behind this:

• Univ. of Tennessee
• Univ. of California Berkeley
• Univ. of Colorado Denver
• NAG Ltd.

📍 Definition at line 92 of file dppt01.f 📍

Definition at line 92 of file dppt01.f. — yes, line 92, bestie. ⭐

💜 Author 💜

Generated automatically by Doxygen for LAPACK from the source code.

---

💖 cute sign-off 💖 This footer is brought to you by LAPACK, Version 3.12.0, with the path /home/abui...IN/dppt01.f(3). The footer doesn’t have a date, so I’m not inventing one — periodt. ✨🎀