TESTING/LIN/dppt02.f(3)

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🦋 TESTING/LIN/dppt02.f(3) 🦋

okay so this is the TESTING/LIN/dppt02.f(3) page from the Library Functions Manual, and it's literally all about DPPT02, bestie. buckle up, it's giving numerical linear algebra but make it cute 💅

✨ NAME ✨

TESTING/LIN/dppt02.f — that's the name, no cap 🎀

🌸 SYNOPSIS 🌸

Functions/Subroutines

   Functions/Subroutines
       subroutine dppt02 (uplo, n, nrhs, a, x, ldx, b, ldb, rwork, resid)
           DPPT02

🧚 Function/Subroutine Documentation 🧚

here's the whole subroutine signature, untouched and iconic:

   subroutine dppt02 (character uplo, integer n, integer nrhs, double
       precision, dimension( * ) a, double precision, dimension( ldx, * ) x,
       integer ldx, double precision, dimension( ldb, * ) b, integer ldb,
       double precision, dimension( * ) rwork, double precision resid)
       DPPT02

DPPT02 is the main character here 👑

💖 Purpose 💖

okay so DPPT02 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 — CHARACTER*1. specifies whether the upper or lower triangular part of the symmetric matrix A is stored:
    • = 'U': Upper triangular
    • = 'L': Lower triangular
  • N — INTEGER. the number of rows and columns of the matrix A. N >= 0.
  • NRHS — INTEGER. the number of columns of B, the matrix of right hand sides. NRHS >= 0.
  • A — DOUBLE PRECISION array, dimension (N*(N+1)/2). the original symmetric matrix A, stored as a packed triangular matrix.
  • X — DOUBLE PRECISION array, dimension (LDX,NRHS). the computed solution vectors for the system of linear equations.
  • LDX — INTEGER. the leading dimension of the array X. LDX >= max(1,N).
  • B — DOUBLE PRECISION 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. important bestie, it gets changed 🫶
  • LDB — INTEGER. the leading dimension of the array B. LDB >= max(1,N).
  • RWORK — DOUBLE PRECISION array, dimension (N).
  • RESID — DOUBLE PRECISION. 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 120 of file dppt02.f.

🌈 Author 🌈

Generated automatically by Doxygen for LAPACK from the source code.

mwah 💋 that's the whole page, from TESTING/LIN/dppt02.f(3), LAPACK Version 3.12.0. slay, you made it to the end, bestie 🫶💖

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