TESTING/LIN/zspt02.f(3)

🎀 TESTING/LIN/zspt02.f(3) — Library Functions Manual

💅 NAME

TESTING/LIN/zspt02.f

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✨ SYNOPSIS

🌸 Functions/Subroutines

subroutine zspt02 (uplo, n, nrhs, a, x, ldx, b, ldb, rwork, resid)
    ZSPT02

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🧚 Function/Subroutine Documentation

subroutine zspt02 (character uplo, integer n, integer nrhs, complex*16,
    dimension( * ) a, complex*16, dimension( ldx, * ) x, integer ldx,
    complex*16, dimension( ldb, * ) b, integer ldb, double precision,
    dimension( * ) rwork, double precision resid)

ZSPT02 — okay bestie, this is the subroutine in question, and it’s giving linear-algebra residual-check realness 💅

🎀 Purpose

So ZSPT02 computes the residual in the solution of a complex 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 complex 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 — COMPLEX*16 array, dimension (N*(N+1)/2); the original complex symmetric matrix A, stored as a packed triangular matrix.
• X — COMPLEX*16 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 — COMPLEX*16 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 — 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 121 of file zspt02.f.

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🌟 Author

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🫶 That’s the whole vibe: LAPACK, Version 3.12.0, page TESTING/LIN/zspt02.f(3). Bye bestie! 💖🎀