SPOTRS(3)

✨ NAME ✨

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

okay so bestie, this is a page from the Library Functions Manual 💖 and the star of the show is that file right up there — that's the whole name section, no cap, it's literally just the path to the Fortran source. She's not mysterious, she's just filed under her address 🏠

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🌸 SYNOPSIS 🌸

Functions/Subroutines

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

• SPOTRS — that's her. the whole point. the moment. 👑

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🦋 Function/Subroutine Documentation 🦋

subroutine SPOTRS (character uplo, integer n, integer nrhs, real, dimension( lda, * ) a, integer lda, real, dimension( ldb, * ) b, integer ldb, integer info)

SPOTRS ✨ — full signature, all seven-ish arguments accounted for, we love a complete cast list 💅

🎀 Purpose 🎀

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

so like — you already did the Cholesky thing with SPOTRF (that's the glow-up prep step, the "getting ready" of linear algebra 💄), and now SPOTRS comes in and actually solves A*X = B for you. symmetric positive definite matrix A, using either A = U**T*U or A = L*L**T. main character energy fr fr 🔥

🌈 Parameters 🌈

• UPLO — CHARACTER*1, the vibe selector for which triangle of A you actually stored. she takes exactly two looks:
  • = 'U': upper triangle of A is stored;
  • = 'L': lower triangle of A is stored.
• N — INTEGER, the order of the matrix A. constraint era: N >= 0 ✨
• NRHS — INTEGER, the number of right hand sides, i.e., the number of columns of the matrix B. also constrained: NRHS >= 0 💖
• A — REAL 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 SPOTRF. so don't hand her a raw matrix, hand her the factorized one, iykyk 🧚
• LDA — INTEGER, the leading dimension of the array A. LDA >= max(1,N) — respect the constraint or she will not be ok 😭
• B — REAL array, dimension (LDB,NRHS). on entry, the right hand side matrix B. on exit, the solution matrix X. she transforms in place, that's the whole trick — B walks in as the question and leaves as the answer 🦋
• LDB — INTEGER, the leading dimension of the array B. LDB >= max(1,N). same energy, same rule 🌸
• INFO — INTEGER, the status report, the vibe check at the end:
  • = 0: successful exit 🎉
  • < 0: if INFO = -i, the i-th argument had an illegal value 💀 (yes, negative — she's pointing at which argument was messy)

👑 Author 👑

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

the whole squad 🫶 listed in that exact order.

Definition at line 109 of file spotrs.f. 📍

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⭐ Author ⭐

Generated automatically by Doxygen for LAPACK from the source code. (yes, a second Author section — the first one is the humans, this one is the robot. both iconic 💅)

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🌸 that's the page!! LAPACK, Version 3.12.0, and the file is /home/abui...RC/spotrs.f(3) — mwah, go solve something symmetric and positive definite bestie 🎀✨