PCDBTRSV(l)

PCDBTRSV(l) — LAPACK routine (version 1.5) 💖

✨ NAME ✨

Okay bestie, so PCDBTRSV is here to solve a banded triangular system of linear equations. The exact vibe is:

A(1:N, JA:JA+N-1) * X = B(IB:IB+N-1, 1:NRHS)

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🌸 SYNOPSIS 🌸

This is the whole signature, no cap:

       SUBROUTINE PCDBTRSV( UPLO, TRANS, N, BWL, BWU, NRHS, A, JA, DESCA, B,
                            IB, DESCB, AF, LAF, WORK, LWORK, INFO )

           CHARACTER        TRANS, UPLO

           INTEGER          BWL, BWU, IB, INFO, JA, LAF, LWORK, N, NRHS

           INTEGER          DESCA( * ), DESCB( * )

           COMPLEX          A( * ), AF( * ), B( * ), WORK( * )

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🦋 PURPOSE 🦋

So PCDBTRSV solves a banded triangular system of linear equations. It can be either:

A(1:N, JA:JA+N-1) * X = B(IB:IB+N-1, 1:NRHS)

or

A(1:N, JA:JA+N-1)^H * X = B(IB:IB+N-1, 1:NRHS)

where A(1:N, JA:JA+N-1) is a banded triangular matrix factor produced by the Gaussian elimination code PC@(dom_pre)BTRF and is stored in A(1:N,JA:JA+N-1) and AF.

The matrix stored in A(1:N, JA:JA+N-1) is either upper or lower triangular according to UPLO, and the choice of solving A(1:N, JA:JA+N-1) or A(1:N, JA:JA+N-1)^H is dictated by the user by the parameter TRANS.

🚨 Bestie, routine PCDBTRF MUST be called first. That's not a suggestion, it's the law. Periodt. 💅

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💖 And that's the tea: LAPACK version 1.5, dated 12 May 1997, and this manual page is PCDBTRSV(l). Stay slay, linear algebra bestie! 🎀✨