SRC/zlantr.f(3)

Welcome to SRC/zlantr.f, bestie — this little icon lives in the Library Functions Manual 💖

✨ NAME ✨

SRC/zlantr.f — that's the name, no cap 🎀

🦋 SYNOPSIS 🦋

🧚 Functions/Subroutines 🧚

double precision function zlantr (norm, uplo, diag, m, n, a, lda, work)

ZLANTR returns the value of the 1-norm, or the Frobenius norm, or the infinity norm, or the element of largest absolute value of a trapezoidal or triangular matrix. Slay 💅

👑 Function/Subroutine Documentation 👑

double precision function zlantr (character norm, character uplo, character diag, integer m, integer n, complex*16, dimension( lda, * ) a, integer lda, double precision, dimension( * ) work)

ZLANTR returns the value of the 1-norm, or the Frobenius norm, or the infinity norm, or the element of largest absolute value of a trapezoidal or triangular matrix. Iconic behavior, honestly ✨

🎯 Purpose 🎯

ZLANTR returns the value of the one norm, or the Frobenius norm, or the infinity norm, or the element of largest absolute value of a trapezoidal or triangular matrix A. Periodt 💖

💅 Returns 💅

Returns: ZLANTR

Here's the exact little decision table, bestie — every branch stays exactly as written 🔥

!>
!>    ZLANTR = ( 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.
!>

Heads up bestie: max(abs(A(i,j))) is not a consistent matrix norm. That's straight from the original, not me being extra 💀

🌈 Parameters 🌈

💜 NORM 💜

NORM is CHARACTER*1.

Specifies the value to be returned in ZLANTR as described above. Choose your norm era wisely ✨

🦋 UPLO 🦋

UPLO is CHARACTER*1.

Specifies whether the matrix A is upper or lower trapezoidal.

• = 'U': Upper trapezoidal
• = 'L': Lower trapezoidal

Note that A is triangular instead of trapezoidal if M = N. Cute little plot twist 🎀

🍓 DIAG 🍓

DIAG is CHARACTER*1.

Specifies whether or not the matrix A has unit diagonal.

• = 'N': Non-unit diagonal
• = 'U': Unit diagonal

🌸 M 🌸

M is INTEGER.

The number of rows of the matrix A. M >= 0, and if UPLO = 'U', M <= N. When M = 0, ZLANTR is set to zero. Respect the zero case, bestie 💅

🌈 N 🌈

N is INTEGER.

The number of columns of the matrix A. N >= 0, and if UPLO = 'L', N <= M. When N = 0, ZLANTR is set to zero. Same energy, different letter ✨

🧚 A 🧚

A is COMPLEX*16 array, dimension (LDA,N).

The trapezoidal matrix A (A is triangular if M = N).

If UPLO = 'U', the leading m by n upper trapezoidal part of the array A contains the upper trapezoidal matrix, and the strictly lower triangular part of A is not referenced.

If UPLO = 'L', the leading m by n lower trapezoidal part of the array A contains the lower trapezoidal matrix, and the strictly upper triangular part of A is not referenced.

Note that when DIAG = 'U', the diagonal elements of A are not referenced and are assumed to be one. So don't come for those diagonal entries, they're not even invited 🫶

🎀 LDA 🎀

LDA is INTEGER.

The leading dimension of the array A. LDA >= max(M,1). That's the rule, bestie 💖

⭐ WORK ⭐

WORK is DOUBLE PRECISION array, dimension (MAX(1,LWORK)), where LWORK >= M when NORM = 'I'; otherwise, WORK is not referenced. Lowkey only sometimes main character energy 🔥

👑 Author 👑

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

Definition at line 140 of file zlantr.f. 💫

💫 Author 💫

Generated automatically by Doxygen for LAPACK from the source code. No thoughts, just generation 🧚

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