DLANTR(3)

💖 DLANTR(3) — Library Functions Manual 💖

okay bestie, welcome to DLANTR(3) from the Library Functions Manual ✨ this is the LAPACK girlie who tells you the value of a norm for a trapezoidal or triangular matrix, and yes she ate.

🌸 NAME 🌸

The source file path is:

/home/abuild/rpmbuild/BUILD/lapack-static-3.12.0-build/lapack-3.12.0/SRC/dlantr.f

✨ SYNOPSIS ✨

🎀 Functions/Subroutines 🎀

• double precision function DLANTR (norm, uplo, diag, m, n, a, lda, work) — DLANTR 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.

🌈 Function/Subroutine Documentation 🌈

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

This is the full signature, and the function does the exact same thing as the synopsis: it 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

DLANTR 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.

💖 Returns

Returns DLANTR — and here's the exact return-value menu, bestie:

!>
!>    DLANTR = ( 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.
!>

🦋 Parameters

okay parameter roll call, no skipping, we're doing all of them 🫶

• NORM — CHARACTER*1; specifies the value to be returned in DLANTR as described above.
• UPLO — 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.
• DIAG — CHARACTER*1; specifies whether or not the matrix A has unit diagonal.
  • = 'N': Non-unit diagonal
  • = 'U': Unit diagonal
• M — INTEGER; the number of rows of the matrix A. M >= 0, and if UPLO = 'U', M <= N. When M = 0, DLANTR is set to zero.
• N — INTEGER; the number of columns of the matrix A. N >= 0, and if UPLO = 'L', N <= M. When N = 0, DLANTR is set to zero.
• A — DOUBLE PRECISION 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.
• LDA — INTEGER; the leading dimension of the array A. LDA >= max(M,1).
• WORK — DOUBLE PRECISION array, dimension (MAX(1,LWORK)), where LWORK >= M when NORM = 'I'; otherwise, WORK is not referenced.

👑 Author

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

Definition at line 139 of file dlantr.f.

👑 Author

Generated automatically by Doxygen for LAPACK from the source code.

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kisses bestie 💋 — this was DLANTR(3), signing off from LAPACK Version 3.12.0 and the footer source /home/abui...RC/dlantr.f(3) 🫶✨