TESTING/LIN/spbt02.f(3)

💖 spbt02.f(3) — Library Functions Manual 💖

okay so bestie, this is the page for TESTING/LIN/spbt02.f — yes, the Library Functions Manual is serving looks near the top, and the whole thing is about the SPBT02 subroutine. Lowkey, it's giving numerical residual energy, and honestly? iconic. No cap. ✨

🌸 NAME 🌸

TESTING/LIN/spbt02.f — that's the file, periodt. Library Functions Manual vibes only. 💅

✨ SYNOPSIS ✨

💅 Functions/Subroutines 💅

subroutine spbt02 (uplo, n, kd, nrhs, a, lda, x, ldx, b, ldb, rwork,
    resid)

SPBT02

🦋 Function/Subroutine Documentation 🦋

subroutine spbt02 (character uplo, integer n, integer kd, integer nrhs,
    real, dimension( lda, * ) a, integer lda, real, dimension( ldx, * ) x,
    integer ldx, real, dimension( ldb, * ) b, integer ldb, real, dimension(
    * ) rwork, real resid)

SPBT02

💖 Purpose 💖

okay so SPBT02 computes the residual for a solution of a symmetric banded system of equations A*x = b:

RESID = norm( B - A*X ) / ( norm(A) * norm(X) * EPS)

where EPS is the machine precision. Slay. 💅

🎀 Parameters 🎀

• UPLO — UPLO is CHARACTER*1. Specifies whether the upper or lower triangular part of the symmetric matrix A is stored:
  • = 'U': Upper triangular
  • = 'L': Lower triangular
• N — N is INTEGER. The number of rows and columns of the matrix A. N >= 0.
• KD — KD is INTEGER. The number of super-diagonals of the matrix A if UPLO = 'U', or the number of sub-diagonals if UPLO = 'L'. KD >= 0.
• NRHS — NRHS is INTEGER. The number of right hand sides. NRHS >= 0.
• A — A is REAL array, dimension (LDA,N). The original symmetric band matrix A, the main character. If UPLO = 'U', the upper triangular part of A is stored as a band matrix; if UPLO = 'L', the lower triangular part of A is stored. The columns of the appropriate triangle are stored in the columns of A and the diagonals of the triangle are stored in the rows of A. See SPBTRF for further details.
• LDA — LDA is INTEGER. The leading dimension of the array A. LDA >= max(1,KD+1).
• X — X is REAL array, dimension (LDX,NRHS). The computed solution vectors for the system of linear equations.
• LDX — LDX is INTEGER. The leading dimension of the array X. LDX >= max(1,N).
• B — B is REAL array, dimension (LDB,NRHS). On entry, the right hand side vectors for the system of linear equations. On exit, B is overwritten with the difference B - A*X.
• LDB — LDB is INTEGER. The leading dimension of the array B. LDB >= max(1,N).
• RWORK — RWORK is REAL array, dimension (N).
• RESID — RESID is REAL. The maximum over the number of right hand sides of norm(B - A*X) / ( norm(A) * norm(X) * EPS ).

👑 Author 👑

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

Definition at line 134 of file spbt02.f.

🌈 Author 🌈

Generated automatically by Doxygen for LAPACK from the source code.

---

Mwah 💋 — this page is from LAPACK Version 3.12.0, and the file on deck is TESTING/LIN/spbt02.f(3). Byeee, bestie 🫶✨