TESTING/LIN/sgtt01.f(3)

okay bestie, this is TESTING/LIN/sgtt01.f(3) from the Library Functions Manual, and it’s giving “LAPACK testing routine with main character energy” 💅✨

💖 NAME 💖

TESTING/LIN/sgtt01.f

✨ SYNOPSIS ✨

Functions/Subroutines

• subroutine sgtt01 (n, dl, d, du, dlf, df, duf, du2, ipiv, work, ldwork, rwork, resid) — SGTT01

🦋 Function/Subroutine Documentation 🦋

subroutine sgtt01 (integer n, real, dimension( * ) dl, real, dimension( * )
    d, real, dimension( * ) du, real, dimension( * ) dlf, real, dimension( *
    ) df, real, dimension( * ) duf, real, dimension( * ) du2, integer,
    dimension( * ) ipiv, real, dimension( ldwork, * ) work, integer ldwork,
    real, dimension( * ) rwork, real resid)

SGTT01

🎯 Purpose 🎯

okay so SGTT01 reconstructs a tridiagonal matrix A from its LU factorization, and then it computes the residual:

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

where EPS is the machine epsilon. no cap, that’s the whole vibe check 🔥

🌸 Parameters 🌸

N

N is INTEGER. It’s the order of matrix A, and N >= 0. periodt.

DL

DL is a REAL array, dimension (N-1). It holds the (n-1) sub-diagonal elements of A 🫶

D

D is a REAL array, dimension (N). It holds the diagonal elements of A ✨

DU

DU is a REAL array, dimension (N-1). It holds the (n-1) super-diagonal elements of A 🌈

DLF

DLF is a REAL array, dimension (N-1). These are the (n-1) multipliers that define the matrix L from the LU factorization of A 💅

DF

DF is a REAL array, dimension (N). It has the n diagonal elements of the upper triangular matrix U from the LU factorization of A 👑

DUF

DUF is a REAL array, dimension (N-1). It holds the (n-1) elements of the first super-diagonal of U ⭐

DU2

DU2 is a REAL array, dimension (N-2). It holds the (n-2) elements of the second super-diagonal of U 🦋

IPIV

IPIV is an INTEGER array, dimension (N). These are 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. iykyk 🧚

WORK

WORK is a REAL array, dimension (LDWORK,N) 💜

LDWORK

LDWORK is INTEGER. It’s the leading dimension of the array WORK, and LDWORK >= max(1,N) 🎀

RWORK

RWORK is a REAL array, dimension (N) 🌸

RESID

RESID is REAL. It’s 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 sgtt01.f.

👑 Author 👑

Generated automatically by Doxygen for LAPACK from the source code.

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and that’s the tea, bestie 🫶 this page is from LAPACK Version 3.12.0, TESTING/LIN/sgtt01.f(3) — slay and stay numeric 💅✨