TESTING/LIN/sppt02.f(3)

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✨ TESTING/LIN/sppt02.f(3) ✨

okay bestie, welcome to the Library Functions Manual page for TESTING/LIN/sppt02.f 🫶 this whole page is about the subroutine sppt02, and it is literally giving “packed symmetric linear system residual check” energy. let’s get into it 💅

🌟 NAME

  • TESTING/LIN/sppt02.f

✨ SYNOPSIS

🧚 Functions/Subroutines

subroutine sppt02 (uplo, n, nrhs, a, x, ldx, b, ldb, rwork, resid)

SPPT02 💖

🌸 Function/Subroutine Documentation

subroutine sppt02 (character uplo, integer n, integer nrhs, real, dimension( * ) a, real, dimension( ldx, * ) x, integer ldx, real, dimension( ldb, * ) b, integer ldb, real, dimension( * ) rwork, real resid)

SPPT02 💅

🎯 Purpose

okay so SPPT02 computes the residual in the solution of a symmetric system of linear equations A*x = b when packed storage is used for the coefficient matrix. the ratio computed is:

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

where EPS is the machine precision. periodt ✨

💖 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.

NRHS

  • NRHS is INTEGER — the number of columns of B, the matrix of right hand sides. NRHS >= 0.

A

  • A is REAL array, dimension (N*(N+1)/2) — the original symmetric matrix A, stored as a packed triangular matrix.

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) — that’s the whole spec, no extra lore 💅

RESID

  • RESID is REAL — the maximum over the number of right hand sides of norm(B - A*X) / ( norm(A) * norm(X) * EPS ).

👑

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

Definition at line 120 of file sppt02.f.

🌈 Author

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mwah 💋 signing off with the footer facts, bestie: this iconic page is from LAPACK Version 3.12.0 and TESTING/LIN/sppt02.f(3) 🎀🦋🌸

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