TESTING/LIN/slaptm.f(3)

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version 3.12.1 · 3 versions
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🌸 NAME 🌸

TESTING/LIN/slaptm.f — welcome to the TESTING/LIN/slaptm.f(3) page from the Library Functions Manual, bestie. This is the whole slaptm situation, and it’s lowkey iconic: symmetric tridiagonal matrix multiply in the LAPACK testing/LIN corner. 💅

✨ SYNOPSIS ✨

🎀 Functions/Subroutines 🎀

       subroutine slaptm (n, nrhs, alpha, d, e, x, ldx, beta, b, ldb)
           SLAPTM

💖 Function/Subroutine Documentation 💖

Okay so here’s the full signature, exactly as it’s giving:

   subroutine slaptm (integer n, integer nrhs, real alpha, real, dimension( * )
       d, real, dimension( * ) e, real, dimension( ldx, * ) x, integer ldx,
       real beta, real, dimension( ldb, * ) b, integer ldb)
       SLAPTM

🦋 Purpose 🦋

slaptm multiplies an N by NRHS matrix X by a symmetric tridiagonal matrix A, then stores the result in a matrix B. The operation has the form:

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

where alpha may be either 1. or -1., and beta may be 0., 1., or -1. No cap. ✨

🌈 Parameters 🌈

🌟 N

N is INTEGER. It’s the order of the matrix A. Constraint: N >= 0.

🌟 NRHS

NRHS is INTEGER. It’s the number of right hand sides, aka the number of columns of the matrices X and B.

🌟 ALPHA

ALPHA is REAL. The scalar alpha. ALPHA must be 1. or -1.; otherwise, it is assumed to be 0.

🌟 D

D is REAL array, dimension (N). The n diagonal elements of the tridiagonal matrix A.

🌟 E

E is REAL array, dimension (N-1). The (n-1) subdiagonal or superdiagonal elements of A.

🌟 X

X is REAL array, dimension (LDX,NRHS). It’s the N by NRHS matrix X.

🌟 LDX

LDX is INTEGER. The leading dimension of the array X. Constraint: 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, it’s 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. Constraint: LDB >= max(N,1).

👑 Author 👑

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

Definition at line 115 of file slaptm.f.

🌈 Author 🌈

Generated automatically by Doxygen for LAPACK from the source code.

LAPACK Version 3.12.0, generated from the source code — the footer doesn’t give a date, so I’m not making one up, periodt. 🫶✨💖

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