TESTING/LIN/cgtt01.f(3)

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💅 TESTING/LIN/cgtt01.f(3) 💅

okay so welcome to the Library Functions Manual page for TESTING/LIN/cgtt01.f, bestie — this is the cgtt01 function page, aka CGTT01, and we are keeping every single detail intact. No cap. 💖

✨ NAME ✨

TESTING/LIN/cgtt01.f — the file page for cgtt01, aka CGTT01. 💫

🌸 SYNOPSIS 🌸

✨ Functions/Subroutines ✨

  • subroutine cgtt01 — CGTT01
subroutine cgtt01 (n, dl, d, du, dlf, df, duf, du2, ipiv, work, ldwork,
    rwork, resid)

💫 Function/Subroutine Documentation 💫

subroutine cgtt01 (integer n, complex, dimension( * ) dl, complex,
    dimension( * ) d, complex, dimension( * ) du, complex, dimension( * )
    dlf, complex, dimension( * ) df, complex, dimension( * ) duf, complex,
    dimension( * ) du2, integer, dimension( * ) ipiv, complex, dimension(
    ldwork, * ) work, integer ldwork, real, dimension( * ) rwork, real
    resid)

CGTT01

🎀 Purpose 🎀

Okay so CGTT01 reconstructs a tridiagonal matrix A from its LU factorization and computes the residual

norm(L*U - A) / ( norm(A) * EPS ),

where EPS is the machine epsilon. 💅

🧚 Parameters 🧚

  • N — is INTEGER; the order of the matrix A. N >= 0.
  • DL — is COMPLEX array, dimension (N-1); the (n-1) sub-diagonal elements of A.
  • D — is COMPLEX array, dimension (N); the diagonal elements of A.
  • DU — is COMPLEX array, dimension (N-1); the (n-1) super-diagonal elements of A.
  • DLF — is COMPLEX array, dimension (N-1); the (n-1) multipliers that define the matrix L from the LU factorization of A.
  • DF — is COMPLEX array, dimension (N); the n diagonal elements of the upper triangular matrix U from the LU factorization of A.
  • DUF — is COMPLEX array, dimension (N-1); the (n-1) elements of the first super-diagonal of U.
  • DU2 — is COMPLEX array, dimension (N-2); the (n-2) elements of the second super-diagonal of U.
  • IPIV — is INTEGER array, dimension (N); the pivot indices; for 1 <= i <= n, row i of the matrix was interchanged with row IPIV(i). IPIV(i) will always be either i or i+1; IPIV(i) = i indicates a row interchange was not required.
  • WORK — is COMPLEX array, dimension (LDWORK,N).
  • LDWORK — is INTEGER; the leading dimension of the array WORK. LDWORK >= max(1,N).
  • RWORK — is REAL array, dimension (N).
  • RESID — is REAL; the scaled residual: norm(L*U - A) / (norm(A) * EPS).

👑 Author 👑

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

Definition at line 132 of file cgtt01.f.

🌈 Author 🌈

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okay bye bestie — this page is from LAPACK, Version 3.12.0, for TESTING/LIN/cgtt01.f(3). The original footer didn't print a date, so I'm not inventing one, fr fr. 💖✨

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