/home/abui.../dsytri2.f(3)

💅 NAME 💅

/home/abuild/rpmbuild/BUILD/lapack-static-3.12.0-build/lapack-3.12.0/SRC/dsytri2.f

okay so this page is from the LAPACK Library Functions Manual, and bestie, it's literally the whole file path, that's the name, that's it, that's the bit 🎀

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✨ SYNOPSIS ✨

🌸 Functions/Subroutines 🌸

subroutine DSYTRI2 (uplo, n, a, lda, ipiv, work, lwork, info)

DSYTRI2 — yep, that's her, that's the whole vibe 👑

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🦋 Function/Subroutine Documentation 🦋

subroutine DSYTRI2 (character uplo, integer n, double precision, dimension(
    lda, * ) a, integer lda, integer, dimension( * ) ipiv, double precision,
    dimension( * ) work, integer lwork, integer info)

DSYTRI2

💜 Purpose: 💜

!> !> DSYTRI2 computes the inverse of a DOUBLE PRECISION symmetric indefinite matrix !> A using the factorization A = U*D*U**T or A = L*D*L**T computed by !> DSYTRF. DSYTRI2 sets the LEADING DIMENSION of the workspace !> before calling DSYTRI2X that actually computes the inverse. !>

so real talk: DSYTRI2 reverses a DOUBLE PRECISION symmetric indefinite matrix A, using the factorization A = U*D*U**T or A = L*D*L**T that DSYTRF already handed you. and the little plot twist — she sets the LEADING DIMENSION of the workspace, then passes the whole thing off to DSYTRI2X, which is the one who actually computes the inverse. middle-management energy but we respect it 💅

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🎀 Parameters 🎀

• UPLO — UPLO is CHARACTER*1. tells us whether the factorization details are chillin' 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.
• N — N is INTEGER. the order of the matrix A. N >= 0.
• A — A is DOUBLE PRECISION array, dimension (LDA,N).
  • On entry: the block diagonal matrix D and the multipliers used to obtain the factor U or L as computed by DSYTRF.
  • On exit, if INFO = 0: the (symmetric) inverse of the original matrix. If UPLO = 'U', the upper triangular part of the inverse is formed and the part of A below the diagonal is not referenced; if UPLO = 'L' the lower triangular part of the inverse is formed and the part of A above the diagonal is not referenced. 🙈 like, don't even look at it.
• LDA — LDA is INTEGER. the leading dimension of the array A. LDA >= max(1,N).
• IPIV — IPIV is INTEGER array, dimension (N). all the deets on the interchanges and the block structure of D, as determined by DSYTRF. iykyk 🫶
• WORK — WORK is DOUBLE PRECISION array, dimension (N+NB+1)*(NB+3).
• LWORK — LWORK is INTEGER. the dimension of the array WORK. WORK is size >= (N+NB+1)*(NB+3). and if LWORK = -1, a workspace query is assumed — the routine:
  • calculates the optimal size of the WORK array, and returns this value as the first entry of the WORK array,
  • and no error message related to LWORK is issued by XERBLA. ✨ no notes, no yelling ✨
• INFO — INFO is INTEGER.
  • = 0: successful exit 🎉
  • < 0: if INFO = -i, the i-th argument had an illegal value 😭
  • > 0: if INFO = i, D(i,i) = 0; the matrix is singular and its inverse could not be computed. 💀 she's singular, bestie, there is no inverse, periodt.

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👑 Author 👑

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

Definition at line 126 of file dsytri2.f.

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🌈 Author 🌈

Generated automatically by Doxygen for LAPACK from the source code. not a human, just a robot doing its little robot thing 🤖💖

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and that's the whole page, bestie — omg wait, one last thing: this is LAPACK, Version 3.12.0, served fresh from /home/abui.../dsytri2.f(3). mwah, go invert something symmetric 💋🦋🌸