/home/abui...a_2stage.f(3)

💖 NAME 💖

okay bestie, this is a Library Functions Manual page for /home/abui...a_2stage.f(3). the actual NAME on the page is the full source path:

/home/abuild/rpmbuild/BUILD/lapack-static-3.12.0-build/lapack-3.12.0/SRC/chesv_aa_2stage.f

that’s the name. that’s the whole name. periodt. 💅

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✨ SYNOPSIS ✨

🧚 Functions/Subroutines 🧚

here’s the synopsis, kept exact so nobody has to guess:

       subroutine CHESV_AA_2STAGE (uplo, n, nrhs, a, lda, tb, ltb, ipiv, ipiv2,
           b, ldb, work, lwork, info)
            CHESV_AA_2STAGE computes the solution to system of linear equations
           A * X = B for HE matrices

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🦋 Function/Subroutine Documentation 🦋

🎀 subroutine CHESV_AA_2STAGE 🎀

   subroutine CHESV_AA_2STAGE (character uplo, integer n, integer nrhs,
       complex, dimension( lda, * ) a, integer lda, complex, dimension( * ) tb,
       integer ltb, integer, dimension( * ) ipiv, integer, dimension( * )
       ipiv2, complex, dimension( ldb, * ) b, integer ldb, complex, dimension(
       * ) work, integer lwork, integer info)

CHESV_AA_2STAGE computes the solution to system of linear equations A * X = B for HE matrices

🌟 Purpose 🌟

so the vibe is: CHESV_AA_2STAGE computes the solution to a complex system of linear equations A * X = B, where A is an N-by-N Hermitian matrix and X and B are N-by-NRHS matrices. iconic linear algebra behavior, honestly.

Aasen's 2-stage algorithm is used to factor A as:

A = U**H * T * U, if UPLO = 'U', or

A = L * T * L**H, if UPLO = 'L',

where U (or L) is a product of permutation and unit upper (lower) triangular matrices, and T is Hermitian and band. The matrix T is then LU-factored with partial pivoting. The factored form of A is then used to solve the system of equations A * X = B.

This is the blocked version of the algorithm, calling Level 3 BLAS. slay. ✨

🎀 Parameters 🎀

• UPLO — CHARACTER*1
  • = 'U': Upper triangle of A is stored;
  • = 'L': Lower triangle of A is stored.
• N — INTEGER; the order of the matrix A. N >= 0.
• NRHS — INTEGER; the number of right hand sides, i.e., the number of columns of the matrix B. NRHS >= 0.
• A — COMPLEX array, dimension (LDA,N); on entry, the hermitian matrix A. If UPLO = 'U', the leading N-by-N upper triangular part of A contains the upper triangular part of the matrix A, and the strictly lower triangular part of A is not referenced. If UPLO = 'L', the leading N-by-N lower triangular part of A contains the lower triangular part of the matrix A, and the strictly upper triangular part of A is not referenced. On exit, L is stored below (or above) the subdiagonal blocks, when UPLO is 'L' (or 'U').
• LDA — INTEGER; the leading dimension of the array A. LDA >= max(1,N).
• TB — COMPLEX array, dimension (LTB); on exit, details of the LU factorization of the band matrix.
• LTB — INTEGER; the size of the array TB. LTB >= 4*N, internally used to select NB such that LTB >= (3*NB+1)*N. If LTB = -1, then a workspace query is assumed; the routine only calculates the optimal size of LTB, returns this value as the first entry of TB, and no error message related to LTB is issued by XERBLA.
• IPIV — INTEGER array, dimension (N); on exit, it contains the details of the interchanges, i.e., the row and column k of A were interchanged with the row and column IPIV(k).
• IPIV2 — INTEGER array, dimension (N); on exit, it contains the details of the interchanges, i.e., the row and column k of T were interchanged with the row and column IPIV(k).
• B — COMPLEX array, dimension (LDB,NRHS); on entry, the right hand side matrix B. On exit, the solution matrix X.
• LDB — INTEGER; the leading dimension of the array B. LDB >= max(1,N).
• WORK — COMPLEX workspace of size LWORK.
• LWORK — INTEGER; the size of WORK. LWORK >= N, internally used to select NB such that LWORK >= N*NB. If LWORK = -1, then a workspace query is assumed; the routine only calculates the optimal size of the WORK array, returns this value as the first entry of the WORK array, and no error message related to LWORK is issued by XERBLA.
• INFO — INTEGER
  • = 0: successful exit
  • < 0: if INFO = -i, the i-th argument had an illegal value.
  • > 0: if INFO = i, band LU factorization failed on i-th column

✨ Author ✨

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

Definition at line 183 of file chesv_aa_2stage.f.

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🌈 Author 🌈

Generated automatically by Doxygen for LAPACK from the source code.

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okay that’s the whole page, bestie 🫶 the footer situation is LAPACK Version 3.12.0 and it points back to /home/abui...a_2stage.f(3). no date is printed in the footer, so we’re not inventing one. mwah 💋✨