SRC/chegst.f(3)

✨ NAME ✨

okay so bestie, this page is SRC/chegst.f from the Library Functions Manual. The header says SRC/chegst.f(3), and we're folding that manual name right in here 💅. It's the docs for the LAPACK subroutine chegst, and it's lowkey iconic.

🌸 SYNOPSIS 🌸

✨ Functions/Subroutines ✨

• subroutine chegst (itype, uplo, n, a, lda, b, ldb, info) — CHEGST

🦋 Function/Subroutine Documentation 🦋

subroutine chegst (integer itype, character uplo, integer n, complex, dimension( lda, * ) a, integer lda, complex, dimension( ldb, * ) b, integer ldb, integer info)

CHEGST — that's the subroutine, and it's absolutely main character energy.

✨ Purpose ✨

okay so CHEGST reduces a complex Hermitian-definite generalized eigenproblem to standard form. fr fr.

• If ITYPE = 1, the problem is A*x = lambda*B*x, and A is overwritten by inv(U**H)*A*inv(U) or inv(L)*A*inv(L**H).
• If ITYPE = 2 or 3, the problem is A*B*x = lambda*x or B*A*x = lambda*x, and A is overwritten by U*A*U**H or L**H*A*L.

Also, B must have been previously factorized as U**H*U or L*L**H by CPOTRF. no cap.

💅 Parameters 💅

• ITYPE — ITYPE is INTEGER.
  • = 1: compute inv(U**H)*A*inv(U) or inv(L)*A*inv(L**H);
  • = 2 or 3: compute U*A*U**H or L**H*A*L.
• UPLO — UPLO is CHARACTER*1.
  • = 'U': Upper triangle of A is stored and B is factored as U**H*U;
  • = 'L': Lower triangle of A is stored and B is factored as L*L**H.
• N — N is INTEGER. The order of the matrices A and B. N >= 0.
• A — A is 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, if INFO = 0, the transformed matrix, stored in the same format as A.
• LDA — LDA is INTEGER. The leading dimension of the array A. LDA >= max(1,N).
• B — B is COMPLEX array, dimension (LDB,N). The triangular factor from the Cholesky factorization of B, as returned by CPOTRF. B is modified by the routine but restored on exit.
• LDB — LDB is INTEGER. The leading dimension of the array B. LDB >= max(1,N).
• INFO — INFO is INTEGER.
  • = 0: successful exit
  • < 0: if INFO = -i, the i-th argument had an illegal value

👑 Author 👑

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

Definition at line 127 of file chegst.f.

🎀 Author 🎀

Generated automatically by Doxygen for LAPACK from the source code.

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mwah 💋 source/version footer realness: LAPACK Version 3.12.0, and the page tag is SRC/chegst.f(3). periodt ✨