ZPOT01(3)

✨ zpot01.f(3) — Library Functions Manual ✨

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💖 NAME 💖

This page is literally about this file path, no cap:

/home/abuild/rpmbuild/BUILD/lapack-static-3.12.0-build/lapack-3.12.0/TESTING/LIN/zpot01.f

🦋 SYNOPSIS 🦋

Functions/Subroutines

       subroutine ZPOT01 (uplo, n, a, lda, afac, ldafac, rwork, resid)
           ZPOT01

💅 Function/Subroutine Documentation 💅

Here’s the full signature, bestie — copy it exactly:

   subroutine ZPOT01 (character uplo, integer n, complex*16, dimension( lda, *
       ) a, integer lda, complex*16, dimension( ldafac, * ) afac, integer
       ldafac, double precision, dimension( * ) rwork, double precision resid)
       ZPOT01

🎀 Purpose

ZPOT01 reconstructs a Hermitian positive definite 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, L' is the conjugate transpose of L, and U' is the conjugate transpose of U. Math girlie behavior, honestly. 🧚

🌸 Parameters

• UPLO — CHARACTER*1. Specifies whether the upper or lower triangular part of the Hermitian 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 — COMPLEX*16 array, dimension (LDA,N). The original Hermitian matrix A.
• LDA — INTEGER. The leading dimension of the array A. LDA >= max(1,N)
• AFAC — COMPLEX*16 array, dimension (LDAFAC,N). On entry, the factor L or U from the L * L**H or U**H * U factorization of A. Overwritten with the reconstructed matrix, and then with the difference L * L**H - A (or U**H * U - A).
• LDAFAC — INTEGER. The leading dimension of the array AFAC. LDAFAC >= max(1,N).
• RWORK — DOUBLE PRECISION array, dimension (N).
• RESID — DOUBLE PRECISION.
  • If UPLO = 'L', norm(L * L**H - A) / ( N * norm(A) * EPS )
  • If UPLO = 'U', norm(U**H * U - A) / ( N * norm(A) * EPS )

Yes, AFAC gets overwritten — it comes back as the reconstructed matrix, then as the difference. Iconic, but also: watch out. 👀

👑 Author

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

Definition at line 105 of file zpot01.f.

🌈 Author 🌈

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