CSTT22(3)

✨ CSTT22(3) — cstt22.f, Library Functions Manual ✨

Hi bestie 💖 this page’s header vibe is /home/abui...IG/cstt22.f(3), and it’s from the Library Functions Manual for cstt22.f. The actual NAME line is the long build path below, no cap. 🫶

🌸 NAME 🌸

/home/abuild/rpmbuild/BUILD/lapack-static-3.12.0-build/lapack-3.12.0/TESTING/EIG/cstt22.f — literally that’s the whole name, she’s long and iconic 💅

✨ SYNOPSIS ✨

🦋 Functions/Subroutines 🦋

subroutine CSTT22 (n, m, kband, ad, ae, sd, se, u, ldu, work, ldwork,
    rwork, result)
    CSTT22

🫶 Function/Subroutine Documentation 🫶

subroutine CSTT22 (integer n, integer m, integer kband, real, dimension( * )
    ad, real, dimension( * ) ae, real, dimension( * ) sd, real, dimension( *
    ) se, complex, dimension( ldu, * ) u, integer ldu, complex, dimension(
    ldwork, * ) work, integer ldwork, real, dimension( * ) rwork, real,
    dimension( 2 ) result)
    CSTT22

CSTT22 — yes bestie, that’s the name again, slay ✨

🎀 Purpose 🎀

CSTT22 checks a set of M eigenvalues and eigenvectors,

A U = U S

where A is Hermitian tridiagonal, the columns of U are unitary, and S is diagonal (if KBAND=0) or Hermitian tridiagonal (if KBAND=1). Two tests are performed:

RESULT(1) = | U* A U - S | / ( |A| m ulp )

RESULT(2) = | I - U*U | / ( m ulp )

🌈 Parameters 🌈

• N — N is INTEGER. The size of the matrix. If it is zero, CSTT22 does nothing. It must be at least zero.
• M — M is INTEGER. The number of eigenpairs to check. If it is zero, CSTT22 does nothing. It must be at least zero.
• KBAND — KBAND is INTEGER. The bandwidth of the matrix S. It may only be zero or one. If zero, then S is diagonal, and SE is not referenced. If one, then S is Hermitian tri-diagonal.
• AD — AD is REAL array, dimension (N). The diagonal of the original (unfactored) matrix A. A is assumed to be Hermitian tridiagonal.
• AE — AE is REAL array, dimension (N). The off-diagonal of the original (unfactored) matrix A. A is assumed to be Hermitian tridiagonal. AE(1) is ignored, AE(2) is the (1,2) and (2,1) element, etc.
• SD — SD is REAL array, dimension (N). The diagonal of the (Hermitian tri-) diagonal matrix S.
• SE — SE is REAL array, dimension (N). The off-diagonal of the (Hermitian tri-) diagonal matrix S. Not referenced if KBSND=0. If KBAND=1, then AE(1) is ignored, SE(2) is the (1,2) and (2,1) element, etc.
• U — U is REAL array, dimension (LDU, N). The unitary matrix in the decomposition.
• LDU — LDU is INTEGER. The leading dimension of U. LDU must be at least N.
• WORK — WORK is COMPLEX array, dimension (LDWORK, M+1).
• LDWORK — LDWORK is INTEGER. The leading dimension of WORK. LDWORK must be at least max(1,M).
• RWORK — RWORK is REAL array, dimension (N).
• RESULT — RESULT is REAL array, dimension (2). The values computed by the two tests described above. The values are currently limited to 1/ulp, to avoid overflow.

👑 Author 👑

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

Definition at line 143 of file cstt22.f.

🌟 Author 🌟

Generated automatically by Doxygen for LAPACK from the source code. 💅

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💖 Cute sign-off: the footer says LAPACK, Version 3.12.0, and /home/abui...IG/cstt22.f(3) — periodt, bye bestie! ✨🎀