CGTT01(3)

💅 NAME 💅

ok so this is the manual page for /home/abui...IN/cgtt01.f(3) — it lives in the Library Functions Manual section, bestie. And the star of the show is the file /home/abuild/rpmbuild/BUILD/lapack-static-3.12.0-build/lapack-3.12.0/TESTING/LIN/cgtt01.f, which is a whole lot of path but like… that's literally where it lives, no cap.

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✨ SYNOPSIS ✨

Functions/Subroutines 🫶

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

CGTT01 — that's the girl. main character energy fr fr.

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🎀 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 🌸

!> !> 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. !>

so basically she takes the LU factorization, rebuilds A from it, and then checks how close norm(L*U - A) / ( norm(A) * EPS ) comes out — with EPS being the machine epsilon. vibe check for your factorization, literally.

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🦋 Parameters 🦋

• N — !> N is INTEGER — !> The order of the matrix A. N >= 0. — so like, how big the matrix is. N >= 0 bestie, zero is allowed, negative is NOT the move.
• DL — !> DL is COMPLEX array, dimension (N-1) — !> The (n-1) sub-diagonal elements of A. — the under-the-diagonal girlies, there's N-1 of them.
• D — !> D is COMPLEX array, dimension (N) — !> The diagonal elements of A. — the main diagonal, N of them, iconic.
• DU — !> DU is COMPLEX array, dimension (N-1) — !> The (n-1) super-diagonal elements of A. — the above-the-diagonal ones, N-1 again.
• DLF — !> DLF is COMPLEX array, dimension (N-1) — !> The (n-1) multipliers that define the matrix L from the !> LU factorization of A. — the multipliers doing the defining of L. slay.
• DF — !> DF is COMPLEX array, dimension (N) — !> The n diagonal elements of the upper triangular matrix U from !> the LU factorization of A. — n diagonal elements of U, the upper triangular icon.
• DUF — !> DUF is COMPLEX array, dimension (N-1) — !> The (n-1) elements of the first super-diagonal of U. — first super-diagonal of U, N-1 elements, we love her.
• DU2 — !> DU2 is COMPLEX array, dimension (N-2) — !> The (n-2) elements of the second super-diagonal of U. — second super-diagonal, N-2 elements. note the N-2 ok don't come for me.
• IPIV — !> 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. — so for 1 <= i <= n, row i got swapped with row IPIV(i). and IPIV(i) is always either i or i+1. if IPIV(i) = i then no row interchange was needed, she stayed put 💅
• WORK — !> WORK is COMPLEX array, dimension (LDWORK,N) — that's the workspace, dimension (LDWORK,N).
• LDWORK — !> LDWORK is INTEGER — !> The leading dimension of the array WORK. LDWORK >= max(1,N). — leading dimension of WORK, and it must be LDWORK >= max(1,N) 🔥
• RWORK — !> RWORK is REAL array, dimension (N) — real array, dimension (N), doing real-girl things.
• RESID — !> RESID is REAL — !> The scaled residual: norm(L*U - A) / (norm(A) * EPS) — the moment of truth, the scaled residual, norm(L*U - A) / (norm(A) * EPS). this is THE number.

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👑 Author 👑

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

Definition at line 132 of file cgtt01.f. ⭐

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🌈 Author 🌈

Generated automatically by Doxygen for LAPACK from the source code. not a human, just vibes and a script 🧚

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and that's the whole page bestie 💖 — cute little sign-off: this is LAPACK, Version 3.12.0, dated /home/abui...IN/cgtt01.f(3) 🎀