ZGTT02(3)

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🏷️ NAME

The NAME section is literally one long path, no cap: /home/abuild/rpmbuild/BUILD/lapack-static-3.12.0-build/lapack-3.12.0/TESTING/LIN/zgtt02.f 🫶

🌸 SYNOPSIS 🌸

Functions/Subroutines

subroutine ZGTT02 (trans, n, nrhs, dl, d, du, x, ldx, b, ldb, resid)
    ZGTT02

ZGTT02 — that’s the subroutine, bestie. 💖

💫 Function/Subroutine Documentation 💫

subroutine ZGTT02 (character trans, integer n, integer nrhs, complex*16,
    dimension( * ) dl, complex*16, dimension( * ) d, complex*16, dimension(
    * ) du, complex*16, dimension( ldx, * ) x, integer ldx, complex*16,
    dimension( ldb, * ) b, integer ldb, double precision resid)
    ZGTT02

ZGTT02 — yes, again, the subroutine name. Iconic repetition, honestly. 👑

🎯 Purpose

Okay so ZGTT02 computes the residual for the solution to a tridiagonal system of equations:

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

where EPS is the machine epsilon. ⭐

🧩 Parameters

• TRANS — TRANS is CHARACTER. It specifies the form of the residual:
  • = 'N': B - A * X (No transpose)
  • = 'T': B - A**T * X (Transpose)
  • = 'C': B - A**H * X (Conjugate transpose)
• N — N is INTEGER. The order of the matrix A. Constraint: N >= 0.
• NRHS — NRHS is INTEGER. The number of right hand sides, i.e., the number of columns of the matrices B and X. Constraint: NRHS >= 0.
• DL — DL is COMPLEX*16 array, dimension (N-1). The (n-1) sub-diagonal elements of A.
• D — D is COMPLEX*16 array, dimension (N). The diagonal elements of A.
• DU — DU is COMPLEX*16 array, dimension (N-1). The (n-1) super-diagonal elements of A.
• X — X is COMPLEX*16 array, dimension (LDX,NRHS). The computed solution vectors X.
• LDX — LDX is INTEGER. The leading dimension of the array X. Constraint: LDX >= max(1,N).
• B — B is 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 - op(A)*X.
• LDB — LDB is INTEGER. The leading dimension of the array B. Constraint: LDB >= max(1,N).
• RESID — RESID is DOUBLE PRECISION. norm(B - op(A)*X) / (norm(op(A)) * norm(X) * EPS).

🎓 Author

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

Definition at line 122 of file zgtt02.f. 📍

🪄 Author

Generated automatically by Doxygen for LAPACK from the source code.

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