DLANGE(3)

🌸 NAME 🌸

okay bestie, welcome to the dlange.f(3) page from the Library Functions Manual ✨ (header path, since you asked: /home/abui...RC/dlange.f(3)).

the actual file this page is about is: /home/abuild/rpmbuild/BUILD/lapack-static-3.12.0-build/lapack-3.12.0/SRC/dlange.f

---

✨ SYNOPSIS ✨

🫶 Functions/Subroutines 🫶

• double precision function DLANGE (norm, m, n, a, lda, work) — bestie, DLANGE returns the value of the 1-norm, Frobenius norm, infinity-norm, or the largest absolute value of any element of a general rectangular matrix. 💅

---

💅 Function/Subroutine Documentation 💅

double precision function DLANGE (character norm, integer m, integer n,
    double precision, dimension( lda, * ) a, integer lda, double precision,
    dimension( * ) work)

okay so same energy as above: DLANGE returns the value of the 1-norm, Frobenius norm, infinity-norm, or the largest absolute value of any element of a general rectangular matrix. no cap. 🦋

🎀 Purpose 🎀

DLANGE returns the value of the one norm, or the Frobenius norm, or the infinity norm, or the element of largest absolute value of a real matrix A. that’s the assignment, and it ate. 🔥

🔥 Returns 🔥

DLANGE — here’s the literal formula vibe, preserved exactly so I don’t mess up the parentheses:

!>
!>    DLANGE = ( max(abs(A(i,j))), NORM = 'M' or 'm'
!>             (
!>             ( norm1(A),         NORM = '1', 'O' or 'o'
!>             (
!>             ( normI(A),         NORM = 'I' or 'i'
!>             (
!>             ( normF(A),         NORM = 'F', 'f', 'E' or 'e'
!>
!> where  norm1  denotes the  one norm of a matrix (maximum column sum),
!> normI  denotes the  infinity norm  of a matrix  (maximum row sum) and
!> normF  denotes the  Frobenius norm of a matrix (square root of sum of
!> squares).  Note that  max(abs(A(i,j)))  is not a consistent matrix norm.
!>

quick translation, bestie: norm1 means the one norm of a matrix, aka maximum column sum; normI means the infinity norm, aka maximum row sum; and normF means the Frobenius norm, aka square root of sum of squares.

🚨 tea time: max(abs(A(i,j))) is not a consistent matrix norm. periodt. 💀

👑 Parameters 👑

• NORM — NORM is CHARACTER*1. it specifies the value to be returned in DLANGE as described above. so like, pick your norm era. 💅
• M — M is INTEGER. the number of rows of the matrix A. M >= 0. when M = 0, DLANGE is set to zero. 🫶
• N — N is INTEGER. the number of columns of the matrix A. N >= 0. when N = 0, DLANGE is set to zero. ✨
• A — A is DOUBLE PRECISION array, dimension (LDA,N). the m by n matrix A. 🌸
• LDA — LDA is INTEGER. the leading dimension of the array A. LDA >= max(M,1). 👑
• WORK — WORK is DOUBLE PRECISION array, dimension (MAX(1,LWORK)), where LWORK >= M when NORM = 'I'; otherwise, WORK is not referenced. 🎀

🌈 Author 🌈

the whole squad behind this one:

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

📌 Definition at line 113 of file dlange.f.

---

📝 Author 📝

• Generated automatically by Doxygen for LAPACK from the source code.

---

that’s the whole page, bestie — footer check: LAPACK Version 3.12.0, and the page path is /home/abui...RC/dlange.f(3) 🫶💖🎀