DPOTRS(3)

🦋 DPOTRS(3) — the LAPACK girlies' guide to solving A*X = B 🦋

ok so this page lives in the Library Functions Manual section 3, and it's file dpotrs.f (full path era: /home/abuild/rpmbuild/BUILD/lapack-static-3.12.0-build/lapack-3.12.0/SRC/dpotrs.f). bestie, we're getting into linear algebra territory and honestly? it slaps.

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🌸 NAME 🌸

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

that's the file, that's the vibe, that's the whole identity 💅

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✨ SYNOPSIS ✨

Functions/Subroutines

subroutine DPOTRS (uplo, n, nrhs, a, lda, b, ldb, info)
    DPOTRS

like, that's the whole call. seven-ish args, one dream 🫶

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👑 Function/Subroutine Documentation 👑

subroutine DPOTRS (character uplo, integer n, integer nrhs, double
    precision, dimension( lda, * ) a, integer lda, double precision,
    dimension( ldb, * ) b, integer ldb, integer info)
    DPOTRS

🎀 Purpose 🎀

!> !> DPOTRS solves a system of linear equations A*X = B with a symmetric !> positive definite matrix A using the Cholesky factorization !> A = UT*U or A = L*LT computed by DPOTRF. !>

ok so real talk: you already did the hard part with DPOTRF (that's where the Cholesky factorization A = U**T*U or A = L*L**T comes from, no cap). now DPOTRS swoops in and actually solves A*X = B using the factor you already have. main character energy fr fr ✨

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💜 Parameters 💜

• UPLO — UPLO is CHARACTER*1. it's giving "which triangle are we working with":

!> = 'U': Upper triangle of A is stored; !> = 'L': Lower triangle of A is stored. !>

• N — N is INTEGER. the order of the matrix A. constraint check: N >= 0 🌈

!>

• NRHS — NRHS is INTEGER. the number of right hand sides, i.e., the number of columns of the matrix B. constraint check: NRHS >= 0 💖

!>

• A — A is DOUBLE PRECISION array, dimension (LDA,N). this is the triangular factor U or L from the Cholesky factorization A = U**T*U or A = L*L**T, as computed by DPOTRF. literally the handoff from your last function 🫶

!>

• LDA — LDA is INTEGER. the leading dimension of the array A. rule: LDA >= max(1,N) 👑

!>

• B — B is DOUBLE PRECISION array, dimension (LDB,NRHS). glow-up moment: on entry, the right hand side matrix B; on exit, the solution matrix X. she transforms 💅

!>

• LDB — LDB is INTEGER. the leading dimension of the array B. rule: LDB >= max(1,N) ⭐

!>

• INFO — INFO is INTEGER. the vibe check at the end:

!> = 0: successful exit !> < 0: if INFO = -i, the i-th argument had an illegal value !>

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🧚 Author 🧚

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

(the academic supergroup of LAPACK, we stan 😭🔥)

Definition at line 109 of file dpotrs.f. 📍

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🌺 Author (again, bestie) 🌺

Generated automatically by Doxygen for LAPACK from the source code. not a human, just a very diligent little documentation fairy 🧚✨

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ok that's the whole page!! 🎀 big slay, INFO = 0, A*X = B solved, everybody go home. this page came to you from LAPACK, Version 3.12.0, dated /home/abui...RC/dpotrs.f(3) — mwah, ily, bye 💖🦋💅