DSTT22(3)

💖 NAME 💖

okay so bestie, this is the page for /home/abuild/rpmbuild/BUILD/lapack-static-3.12.0-build/lapack-3.12.0/TESTING/EIG/dstt22.f, and the header energy is /home/abui...IG/dstt22.f(3) from the Library Functions Manual 💅✨.

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✨ SYNOPSIS ✨

Functions/Subroutines

subroutine DSTT22 (n, m, kband, ad, ae, sd, se, u, ldu, work, ldwork,
    result)
    DSTT22

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🛠️ Function/Subroutine Documentation 🛠️

subroutine DSTT22 (integer n, integer m, integer kband, double precision,
    dimension( * ) ad, double precision, dimension( * ) ae, double
    precision, dimension( * ) sd, double precision, dimension( * ) se,
    double precision, dimension( ldu, * ) u, integer ldu, double precision,
    dimension( ldwork, * ) work, integer ldwork, double precision,
    dimension( 2 ) result)
    DSTT22

yep, it’s DSTT22 again — main character energy 👑.

🌸 Purpose 🌸

DSTT22 checks a set of M eigenvalues and eigenvectors, like:

A U = U S

where A is symmetric tridiagonal, the columns of U are orthogonal, and S is diagonal (if KBAND=0) or symmetric tridiagonal (if KBAND=1).

Two tests are performed, bestie:

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, DSTT22 does nothing. It must be at least zero. ✨
• M — M is INTEGER. The number of eigenpairs to check. If it is zero, DSTT22 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 symmetric tri-diagonal. 🦋
• AD — AD is DOUBLE PRECISION array, dimension (N). The diagonal of the original (unfactored) matrix A. A is assumed to be symmetric tridiagonal. 🌸
• AE — AE is DOUBLE PRECISION array, dimension (N). The off-diagonal of the original (unfactored) matrix A. A is assumed to be symmetric tridiagonal. AE(1) is ignored, AE(2) is the (1,2) and (2,1) element, etc. 💫
• SD — SD is DOUBLE PRECISION array, dimension (N). The diagonal of the (symmetric tri-) diagonal matrix S. 🎀
• SE — SE is DOUBLE PRECISION array, dimension (N). The off-diagonal of the (symmetric tri-) diagonal matrix S. Not referenced if KBSND=0 (yes, that’s exactly how it’s written here 👀). If KBAND=1, then AE(1) is ignored, SE(2) is the (1,2) and (2,1) element, etc. 💅
• U — U is DOUBLE PRECISION array, dimension (LDU, N). The orthogonal matrix in the decomposition. 👑
• LDU — LDU is INTEGER. The leading dimension of U. LDU must be at least N. 🔥
• WORK — WORK is DOUBLE PRECISION array, dimension (LDWORK, M+1). 🫶
• LDWORK — LDWORK is INTEGER. The leading dimension of WORK. LDWORK must be at least max(1,M). 🌈
• RESULT — RESULT is DOUBLE PRECISION 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 137 of file dstt22.f. 📌

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🌟 Author 🌟

Generated automatically by Doxygen for LAPACK from the source code.

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Cute sign-off, bestie 🎀: the footer says LAPACK, Version 3.12.0, source path /home/abui...IG/dstt22.f(3), and no separate date is printed there. Go slay those symmetric tridiagonal checks 💅✨