SRC/chfrk.f(3)

💅 SRC/chfrk.f — from the Library Functions Manual ✨

okay bestie, gather round, because this one is a whole mood. It's a page straight out of the Library Functions Manual and it's all about chfrk — a lil' Fortran subroutine that does a Hermitian rank-k operation on a matrix chillin' in RFP format. Sounds scary? It's giving math but we're gonna slay it together. 🫶

---

🌸 NAME 🌸

SRC/chfrk.f — that's the file, that's the name, no notes. 💅

---

✨ SYNOPSIS ✨

Functions/Subroutines

• subroutine chfrk (transr, uplo, trans, n, k, alpha, a, lda, beta, c) — CHFRK performs a Hermitian rank-k operation for matrix in RFP format. that's literally the whole vibe. 🎀

---

🦋 Function/Subroutine Documentation 🦋

subroutine chfrk (character transr, character uplo, character trans, integer
    n, integer k, real alpha, complex, dimension( lda, * ) a, integer lda,
    real beta, complex, dimension( * ) c)

CHFRK performs a Hermitian rank-k operation for matrix in RFP format. we been knew. 👑

🌈 Purpose 🌈

okay so here's the tea, and I'm quoting the energy of the original comment block exactly:

Level 3 BLAS like routine for C in RFP Format.

CHFRK performs one of the Hermitian rank--k operations:

C := alpha*A*A**H + beta*C,

or

C := alpha*A**H*A + beta*C,

where alpha and beta are real scalars, C is an n--by--n Hermitian matrix and A is an n--by--k matrix in the first case and a k--by--n matrix in the second case. periodt. no cap, that's the whole operation. 💖

---

💜 Parameters 💜

okay the parameter list is long but every single one is iconic in its own way. buckle up. 🎢

🌸 TRANSR

TRANSR is CHARACTER*1

• = 'N': The Normal Form of RFP A is stored;
• = 'C': The Conjugate-transpose Form of RFP A is stored.

🎀 UPLO

UPLO is CHARACTER*1

On entry, UPLO specifies whether the upper or lower triangular part of the array C is to be referenced as follows:

• UPLO = 'U' or 'u' — Only the upper triangular part of C is to be referenced.
• UPLO = 'L' or 'l' — Only the lower triangular part of C is to be referenced.

Unchanged on exit. (it just vibes there the whole time, respectfully 🌸)

🦋 TRANS

TRANS is CHARACTER*1

On entry, TRANS specifies the operation to be performed as follows:

• TRANS = 'N' or 'n' — C := alpha*A*A**H + beta*C.
• TRANS = 'C' or 'c' — C := alpha*A**H*A + beta*C.

Unchanged on exit. ✨

⭐ N

N is INTEGER

On entry, N specifies the order of the matrix C. N must be at least zero. Unchanged on exit. 🔥

💀 K

K is INTEGER

On entry with TRANS = 'N' or 'n', K specifies the number of columns of the matrix A, and on entry with TRANS = 'C' or 'c', K specifies the number of rows of the matrix A. K must be at least zero. Unchanged on exit. 👑

🍓 ALPHA

ALPHA is REAL

On entry, ALPHA specifies the scalar alpha. Unchanged on exit. 🥰

🌈 A

A is COMPLEX array, dimension (LDA,ka)

where KA is K when TRANS = 'N' or 'n', and is N otherwise. Before entry with TRANS = 'N' or 'n', the leading N--by--K part of the array A must contain the matrix A, otherwise the leading K--by--N part of the array A must contain the matrix A. Unchanged on exit. this one's the main character fr fr 💅

🧚 LDA

LDA is INTEGER

On entry, LDA specifies the first dimension of A as declared in the calling (sub) program. When TRANS = 'N' or 'n' then LDA must be at least max( 1, n ), otherwise LDA must be at least max( 1, k ). Unchanged on exit. 🎀

🙈 BETA

BETA is REAL

On entry, BETA specifies the scalar beta. Unchanged on exit. ⭐

👑 C

C is COMPLEX array, dimension (N*(N+1)/2)

On entry, the matrix A in RFP Format. RFP Format is described by TRANSR, UPLO and N. Note that the imaginary parts of the diagonal elements need not be set, they are assumed to be zero, and on exit they are set to zero. lowkey important, highkey iconic. 😭

---

🫶 Author 🫶

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

Definition at line 166 of file chfrk.f. 🎯

---

💖 Author (again, yes really) 💖

Generated automatically by Doxygen for LAPACK from the source code. the robots wrote this one, respectfully. 🤖✨

---

and that's the page bestie!! 🌸 Version 3.12.0 of LAPACK, dated to match SRC/chfrk.f(3) — mwah, go forth and multiply your Hermitian matrices responsibly. 💅🎀🦋