SLAGTM(3)

💅 SLAGTM(3) — Library Functions Manual

okay bestie, pull up a chair 🎀 this is the SLAGTM(3) page, and it’s giving tridiagonal matrix product but make it LAPACK. No cap, every flag and parameter is below.

🎀 NAME

/home/abuild/rpmbuild/BUILD/lapack-static-3.12.0-build/lapack-3.12.0/SRC/slagtm.f

✨ SYNOPSIS

🧚 Functions/Subroutines

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

SLAGTM 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. ✨

💖 Function/Subroutine Documentation

   subroutine SLAGTM (character trans, integer n, integer nrhs, real alpha,
       real, dimension( * ) dl, real, dimension( * ) d, real, dimension( * )
       du, real, dimension( ldx, * ) x, integer ldx, real beta, real,
       dimension( ldb, * ) b, integer ldb)

Same vibe as the synopsis: SLAGTM 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. 💅

🌸 Purpose

ok so the actual operation is:

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

where:

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

That’s the whole main character moment. 🫶

🦋 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'* X + beta * B
  • = 'C': Conjugate transpose = Transpose
• 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 REAL. The scalar alpha. ALPHA must be 0., 1., or -1.; otherwise, it is assumed to be 0. 🚨
• DL — DL is REAL array, dimension (N-1). The (n-1) sub-diagonal elements of T.
• D — D is REAL array, dimension (N). The diagonal elements of T.
• DU — DU is REAL array, dimension (N-1). The (n-1) super-diagonal elements of T.
• X — X is REAL 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 REAL. The scalar beta. BETA must be 0., 1., or -1.; otherwise, it is assumed to be 1. 🚨
• B — B is REAL 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 slagtm.f.

Definition at line 143 of file slagtm.f. — yes, exactly that. 🫡

🧚 Author

Generated automatically by Doxygen for LAPACK from the source code.

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ok bestie, that’s the whole page 💖 cute sign-off time: LAPACK Version 3.12.0, footer path /home/abui...RC/slagtm.f(3), and the footer doesn’t list a date — so no invented date, just vibes. 🌈👑