?lantr

Developer Reference for Intel® oneAPI Math Kernel Library for Fortran

Download PDF

ID 766686

Date 4/28/2026

Version

Public

?lantr

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.

Syntax

valslantr ( norm , uplo , diag , m , n , a , lda , work )

valdlantr ( norm , uplo , diag , m , n , a , lda , work )

valclantr ( norm , uplo , diag , m , n , a , lda , work )

valzlantr ( norm , uplo , diag , m , n , a , lda , work )

Include Files

mkl.fi

Description

slantr dlantr clantr zlantr

The function ?lantr 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 A .

Input Parameters

The data types are given for the Fortran interface.

norm

CHARACTER*1 . Specifies the value to be returned by the routine:

= ‘M’ or ‘m’: val = max(abs(A_{ij})) , largest absolute value of the matrix A . = ‘1’ or ‘O’ or ‘o’: val = norm1(A) , 1-norm of the matrix A (maximum column sum), = ‘I’ or ‘i’: val = normI(A) , infinity norm of the matrix A (maximum row sum), = ‘F’ , ‘f’ , ‘E’ or ‘e’: val = normF(A) , Frobenius norm of the matrix A (square root of sum of squares).

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 , ?lantr 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 , ?lantr is set to zero.

a: REAL for slantr DOUBLE PRECISION for dlantr COMPLEX for clantr DOUBLE COMPLEX for zlantr Array, DIMENSION ( lda , n ). Array, size at least max(1, lda*n) for column major and max(1, lda*m) for row major layout. 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: REAL for slantr / clantrp . DOUBLE PRECISION for dlantr / zlantr . Workspace array, DIMENSION (max(1,lwork)) , where lwork≥m when norm = 'I' ; otherwise, work is not referenced.

Output Parameters

val: REAL for slantr / clantrp . DOUBLE PRECISION for dlantr / zlantr . Value returned by the function.

Select Your Language

Using Intel.com Search

Quick Links

Recent Searches

Advanced Search

Only search in

Developer Reference for Intel® oneAPI Math Kernel Library for Fortran

?lantr

Syntax

Include Files

Description

Input Parameters

Output Parameters