TESTING/LIN/zptt02.f(3)

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version 3.12.1 · 2 versions
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🎀 NAME 🎀

TESTING/LIN/zptt02.f — bestie, welcome to the TESTING/LIN/zptt02.f(3) page from the Library Functions Manual. This is the whole LAPACK test-routine vibe, and we are keeping every single detail. ✨

✨ SYNOPSIS ✨

🦋 Functions/Subroutines 🦋

  • subroutine zptt02 (uplo, n, nrhs, d, e, x, ldx, b, ldb, resid) — ZPTT02

💅 Function/Subroutine Documentation 💅

subroutine zptt02 (character uplo, integer n, integer nrhs, double
     precision, dimension( * ) d, complex*16, dimension( * ) e, complex*16,
     dimension( ldx, * ) x, integer ldx, complex*16, dimension( ldb, * ) b,
     integer ldb, double precision resid)

ZPTT02 — iconic name, no notes needed beyond that.

🎯 Purpose 🎯

Okay so ZPTT02 computes the residual for the solution to a symmetric tridiagonal system of equations:

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

where EPS is the machine epsilon. That's the whole math moment. 🔥

🍓 Parameters 🍓

  • UPLO — is CHARACTER*1. It specifies whether the superdiagonal or the subdiagonal of the tridiagonal matrix A is stored. = 'U': E is the superdiagonal of A. = 'L': E is the subdiagonal of A.
  • N — is INTEGER. The order of the matrix A.
  • NRHS — is INTEGER. The number of right hand sides, i.e., the number of columns of the matrices B and X. NRHS >= 0.
  • D — is DOUBLE PRECISION array, dimension (N). The n diagonal elements of the tridiagonal matrix A.
  • E — is COMPLEX*16 array, dimension (N-1). The (n-1) subdiagonal elements of the tridiagonal matrix A.
  • X — is COMPLEX*16 array, dimension (LDX,NRHS). The n by nrhs matrix of solution vectors X.
  • LDX — is INTEGER. The leading dimension of the array X. LDX >= max(1,N).
  • B — is COMPLEX*16 array, dimension (LDB,NRHS). On entry, the n by nrhs matrix of right hand side vectors B. On exit, B is overwritten with the difference B - A*X.
  • LDB — is INTEGER. The leading dimension of the array B. LDB >= max(1,N).
  • RESID — is DOUBLE PRECISION. 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 114 of file zptt02.f.

🌈 Author 🌈

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