SRC/zlagtm.f(3)

🌸 NAME 🌸

hey bestie 💖 this is SRC/zlagtm.f(3) from the Library Functions Manual — the LAPACK page for ZLAGTM, and she is serving tridiagonal matrix-matrix realness, no cap ✨

SRC/zlagtm.f

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✨ SYNOPSIS ✨

🫶 Functions/Subroutines 🫶

subroutine zlagtm (trans, n, nrhs, alpha, dl, d, du, x, ldx, beta, b, ldb)

okay so quick vibe check: ZLAGTM performs a matrix-matrix product of the form C = αAB+βC, where A is a tridiagonal matrix, B and C are rectangular matrices, and α and β are scalars, which may be 0, 1, or -1. 💅

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💖 Function/Subroutine Documentation 💖

🌈 subroutine zlagtm 🌈

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

ZLAGTM performs a matrix-matrix product of the form C = αAB+βC, where A is a tridiagonal matrix, B and C are rectangular matrices, and α and β are scalars, which may be 0, 1, or -1. literally the whole moment 🫶

🦋 Purpose 🦋

okay so the purpose is, literally:

B := alpha * A * X + beta * B

where A is a tridiagonal matrix of order N, B and X are N by NRHS matrices, and alpha and beta are real scalars, each of which may be 0., 1., or -1. ✨

🎀 Parameters 🎀

• TRANS — TRANS is CHARACTER*1. Specifies the operation applied to A.
  • = 'N': No transpose, B := alpha * A * X + beta * B
  • = 'T': Transpose, B := alpha * A**T * X + beta * B
  • = 'C': Conjugate transpose, B := alpha * A**H * X + beta * B
• N — N is INTEGER. The order of the matrix A. N >= 0.
• NRHS — NRHS is INTEGER. The number of right hand sides, i.e., the number of columns of the matrices X and B.
• ALPHA — ALPHA is DOUBLE PRECISION. The scalar alpha. ALPHA must be 0., 1., or -1.; otherwise, it is assumed to be 0.
• DL — DL is COMPLEX*16 array, dimension (N-1). The (n-1) sub-diagonal elements of T.
• D — D is COMPLEX*16 array, dimension (N). The diagonal elements of T.
• DU — DU is COMPLEX*16 array, dimension (N-1). The (n-1) super-diagonal elements of T.
• X — X is COMPLEX*16 array, dimension (LDX,NRHS). The N by NRHS matrix X.
• LDX — LDX is INTEGER. The leading dimension of the array X. LDX >= max(N,1).
• BETA — BETA is DOUBLE PRECISION. The scalar beta. BETA must be 0., 1., or -1.; otherwise, it is assumed to be 1.
• B — B is COMPLEX*16 array, dimension (LDB,NRHS). On entry, the N by NRHS matrix B. On exit, B is overwritten by the matrix expression B := alpha * A * X + beta * B.
• LDB — LDB is INTEGER. The leading dimension of the array B. LDB >= max(N,1).

🌟 Author 🌟

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

Definition at line 143 of file zlagtm.f.

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🎀 Author 🎀

Generated automatically by Doxygen for LAPACK from the source code.

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bye bestie 🫶 the footer says LAPACK Version 3.12.0 and points at SRC/zlagtm.f(3) — there’s no date printed there, so I’m not inventing one, periodt 💅💖