CLAVHP(3)

Hey bestie 💖 you’re looking at CLAVHP(3), a page from the Library Functions Manual. It’s giving LAPACK routine energy, and we’re gonna walk through every single deet together. No cap. ✨

💖 NAME

The NAME section is literally this path, character for character:

/home/abuild/rpmbuild/BUILD/lapack-static-3.12.0-build/lapack-3.12.0/TESTING/LIN/clavhp.f

✨ SYNOPSIS

Under Functions/Subroutines, the synopsis is serving:

Functions/Subroutines
    subroutine CLAVHP (uplo, trans, diag, n, nrhs, a, ipiv, b, ldb, info)
        CLAVHP

🦋 Function/Subroutine Documentation

The full signature is iconic and exact:

subroutine CLAVHP (character uplo, character trans, character diag, integer
    n, integer nrhs, complex, dimension( * ) a, integer, dimension( * )
    ipiv, complex, dimension( ldb, * ) b, integer ldb, integer info)
    CLAVHP

Purpose

Okay so CLAVHP performs one of the matrix-vector operations:

x := A*x  or  x := A^H*x,

where x is an N element vector and A is one of the factors from the symmetric factorization computed by CHPTRF. CHPTRF produces a factorization of the form:

U * D * U^H     or     L * D * L^H,

where U (or L) is a product of permutation and unit upper (lower) triangular matrices, U^H (or L^H) is the conjugate transpose of U (or L), and D is Hermitian and block diagonal with 1 x 1 and 2 x 2 diagonal blocks. The multipliers for the transformations and the upper or lower triangular parts of the diagonal blocks are stored columnwise in packed format in the linear array A.

If TRANS = 'N' or 'n', CLAVHP multiplies either by U or U * D (or L or L * D). If TRANS = 'C' or 'c', CLAVHP multiplies either by U^H or D * U^H (or L^H or D * L^H ).

Here are the arguments, one by one, with all the tea ☕:

• UPLO — CHARACTER*1. On entry, UPLO specifies whether the triangular matrix stored in A is upper or lower triangular. UPLO = 'U' or 'u' means the matrix is upper triangular. UPLO = 'L' or 'l' means the matrix is lower triangular. Unchanged on exit.
• TRANS — CHARACTER*1. On entry, TRANS specifies the operation to be performed as follows: TRANS = 'N' or 'n' means x := A*x. TRANS = 'C' or 'c' means x := A^H*x. Unchanged on exit.
• DIAG — CHARACTER*1. On entry, DIAG specifies whether the diagonal blocks are assumed to be unit matrices, as follows: DIAG = 'U' or 'u' means diagonal blocks are unit matrices. DIAG = 'N' or 'n' means diagonal blocks are non-unit. Unchanged on exit.
• N — INTEGER. On entry, N specifies the order of the matrix A. N must be at least zero. Unchanged on exit.
• NRHS — INTEGER. On entry, NRHS specifies the number of right hand sides, i.e., the number of vectors x to be multiplied by A. NRHS must be at least zero. Unchanged on exit.
• A — COMPLEX array, dimension( N*(N+1)/2 ). On entry, A contains a block diagonal matrix and the multipliers of the transformations used to obtain it, stored as a packed triangular matrix. Unchanged on exit.
• IPIV — INTEGER array, dimension( N ). On entry, IPIV contains the vector of pivot indices as determined by CSPTRF or CHPTRF. If IPIV( K ) = K, no interchange was done. If IPIV( K ) <> K but IPIV( K ) > 0, then row K was interchanged with row IPIV( K ) and a 1 x 1 pivot block was used. If IPIV( K ) < 0 and UPLO = 'U', then row K-1 was exchanged with row | IPIV( K ) | and a 2 x 2 pivot block was used. If IPIV( K ) < 0 and UPLO = 'L', then row K+1 was exchanged with row | IPIV( K ) | and a 2 x 2 pivot block was used.
• B — COMPLEX array, dimension( LDB, NRHS ). On entry, B contains NRHS vectors of length N. On exit, B is overwritten with the product A * B.
• LDB — INTEGER. On entry, LDB contains the leading dimension of B as declared in the calling program. LDB must be at least max( 1, N ). Unchanged on exit.
• INFO — INTEGER. INFO is the error flag. On exit, a value of 0 indicates a successful exit. A negative value, say -K, indicates that the K-th argument has an illegal value.

Author

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

Definition at line 129 of file clavhp.f.

Author

Generated automatically by Doxygen for LAPACK from the source code.

---

💖 That’s the whole page, bestie — LAPACK Version 3.12.0, page source /home/abui...IN/clavhp.f(3). Periodt. 💅