DSPTRS(3)

💅 DSPTRS(3) — like, the Library Functions Manual bestie ✨

okay so picture this: you're deep in /home/abuild/rpmbuild/BUILD/lapack-static-3.12.0-build/lapack-3.12.0/SRC/dsptrs.f and you need the solver. that's this file. welcome 🫶

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🌸 NAME 🌸

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

(yeah bestie, the name is literally the whole path. iconic. no notes. 💀)

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✨ SYNOPSIS ✨

Functions/Subroutines 🧚

subroutine DSPTRS (uplo, n, nrhs, ap, ipiv, b, ldb, info)
    DSPTRS

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👑 Function/Subroutine Documentation 👑

subroutine DSPTRS (character uplo, integer n, integer nrhs, double
    precision, dimension( * ) ap, integer, dimension( * ) ipiv, double
    precision, dimension( ldb, * ) b, integer ldb, integer info)
    DSPTRS

🎀 Purpose 🎀

!>
!> DSPTRS solves a system of linear equations A*X = B with a real
!> symmetric matrix A stored in packed format using the factorization
!> A = U*D*U**T or A = L*D*L**T computed by DSPTRF.
!>

so like, DSPTRS solves A*X = B where A is a real symmetric matrix stored in packed format, using the factorization A = U*D*U**T or A = L*D*L**T that DSPTRF already handed you. it's giving "i already did the hard part, you're welcome" 💅✨

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🌈 Parameters 🌈

💖 UPLO

!>          UPLO is CHARACTER*1
!>          Specifies whether the details of the factorization are stored
!>          as an upper or lower triangular matrix.
!>          = 'U':  Upper triangular, form is A = U*D*U**T;
!>          = 'L':  Lower triangular, form is A = L*D*L**T.
!>

• UPLO is CHARACTER*1 — it tells us whether the factorization deets live in an upper or lower triangular matrix, bestie.
  • = 'U': upper triangular, form is A = U*D*U**T
  • = 'L': lower triangular, form is A = L*D*L**T

🦋 N

!>          N is INTEGER
!>          The order of the matrix A.  N >= 0.
!>

• N is INTEGER — the order of the matrix A, and N >= 0 fr fr. (no negative orders, we don't do that here 🙈)

🌸 NRHS

!>          NRHS is INTEGER
!>          The number of right hand sides, i.e., the number of columns
!>          of the matrix B.  NRHS >= 0.
!>

• NRHS is INTEGER — how many right hand sides you got, i.e. the number of columns of the matrix B. and yes, NRHS >= 0. 🫶

🍓 AP

!>          AP is DOUBLE PRECISION array, dimension (N*(N+1)/2)
!>          The block diagonal matrix D and the multipliers used to
!>          obtain the factor U or L as computed by DSPTRF, stored as a
!>          packed triangular matrix.
!>

• AP is a DOUBLE PRECISION array, dimension (N*(N+1)/2) — it holds the block diagonal matrix D plus the multipliers used to obtain the factor U or L as computed by DSPTRF, all stored as a packed triangular matrix. packed! lowkey efficient 💅

🧚 IPIV

!>          IPIV is INTEGER array, dimension (N)
!>          Details of the interchanges and the block structure of D
!>          as determined by DSPTRF.
!>

• IPIV is an INTEGER array, dimension (N) — the details of the interchanges and the block structure of D, as determined by DSPTRF. the receipts, basically. 🧾✨

⭐ B

!>          B is DOUBLE PRECISION array, dimension (LDB,NRHS)
!>          On entry, the right hand side matrix B.
!>          On exit, the solution matrix X.
!>

• B is a DOUBLE PRECISION array, dimension (LDB,NRHS).
  • on entry: the right hand side matrix B 🫡
  • on exit: the solution matrix X — glow-up moment, main character energy 👑

🔥 LDB

!>          LDB is INTEGER
!>          The leading dimension of the array B.  LDB >= max(1,N).
!>

• LDB is INTEGER — the leading dimension of the array B, and you must have LDB >= max(1,N). no cap. 🔥

💜 INFO

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

• INFO is INTEGER:
  • = 0: successful exit, we ate and left no crumbs 🎀
  • < 0: if INFO = -i, then the i-th argument had an illegal value 💀 (not me passing a bad argument…)

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🫶 Author 🫶

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

(the whole squad showed up. legends only. 👑)

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🦋 Definition at line 114 of file dsptrs.f. 🦋

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💌 Author 💌

Generated automatically by Doxygen for LAPACK from the source code. (yes queen, the robots wrote the docs too 🤖✨)

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and that's the whole vibe check, bestie 💖 one last cute sign-off: this little masterpiece is LAPACK, Version 3.12.0, living its best life over at /home/abui...RC/dsptrs.f(3). slay, bye! 🌈🦋💅