TESTING/EIG/dget54.f(3)

💖 TESTING/EIG/dget54.f 💖

okay bestie, this page is from the Library Functions Manual, and the main character is TESTING/EIG/dget54.f — the DGET54 subroutine. It's giving LAPACK testing energy and honestly? iconic. 🫶

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✨ SYNOPSIS ✨

🎀 Functions/Subroutines 🎀

subroutine dget54 (n, a, lda, b, ldb, s, lds, t, ldt, u, ldu, v, ldv,
    work, result)
    DGET54

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🦋 Function/Subroutine Documentation 🦋

subroutine dget54 (integer n, double precision, dimension( lda, * ) a,
    integer lda, double precision, dimension( ldb, * ) b, integer ldb,
    double precision, dimension( lds, * ) s, integer lds, double precision,
    dimension( ldt, * ) t, integer ldt, double precision, dimension( ldu, *
    ) u, integer ldu, double precision, dimension( ldv, * ) v, integer ldv,
    double precision, dimension( * ) work, double precision result)

DGET54 is the name, and checking decompositions is the game. 💅

🎀 Purpose 🎀

DGET54 checks a generalized decomposition of the form

A = U*S*V'  and B = U*T* V'

where ' means transpose and U and V are orthogonal. no cap, that apostrophe is doing important work. 😌

Specifically,

RESULT = ||( A - U*S*V', B - U*T*V' )|| / (||( A, B )||*n*ulp )

💅 Parameters 💅

• N — N is INTEGER. The size of the matrix. If it is zero, DGET54 does nothing. It must be at least zero.
• A — A is DOUBLE PRECISION array, dimension (LDA, N). The original (unfactored) matrix A.
• LDA — LDA is INTEGER. The leading dimension of A. It must be at least 1 and at least N.
• B — B is DOUBLE PRECISION array, dimension (LDB, N). The original (unfactored) matrix B.
• LDB — LDB is INTEGER. The leading dimension of B. It must be at least 1 and at least N.
• S — S is DOUBLE PRECISION array, dimension (LDS, N). The factored matrix S.
• LDS — LDS is INTEGER. The leading dimension of S. It must be at least 1 and at least N.
• T — T is DOUBLE PRECISION array, dimension (LDT, N). The factored matrix T.
• LDT — LDT is INTEGER. The leading dimension of T. It must be at least 1 and at least N.
• U — U is DOUBLE PRECISION array, dimension (LDU, N). The orthogonal matrix on the left-hand side in the decomposition.
• LDU — LDU is INTEGER. The leading dimension of U. LDU must be at least N and at least 1.
• V — V is DOUBLE PRECISION array, dimension (LDV, N). The orthogonal matrix on the left-hand side in the decomposition.
• LDV — LDV is INTEGER. The leading dimension of V. LDV must be at least N and at least 1.
• WORK — WORK is DOUBLE PRECISION array, dimension (3*N**2).
• RESULT — RESULT is DOUBLE PRECISION. The value RESULT, It is currently limited to 1/ulp, to avoid overflow. Errors are flagged by RESULT=10/ulp.

👑 Author 👑

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

Definition at line 154 of file dget54.f.

🧚 Author (generated automatically) 🧚

Generated automatically by Doxygen for LAPACK from the source code.

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xoxo, your Unix bestie 💖 — footer vibe check: LAPACK Version 3.12.0, page TESTING/EIG/dget54.f(3). periodt. ✨