?lantp

Developer Reference for Intel® oneAPI Math Kernel Library for Fortran

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ID 766686

Date 4/28/2026

Version

Public

?lantp

Returns the value of the 1-norm, or the Frobenius norm, or the infinity norm, or the element of largest absolute value of a triangular matrix supplied in packed form.

Syntax

valslantp ( norm , uplo , diag , n , ap , work )

valdlantp ( norm , uplo , diag , n , ap , work )

valclantp ( norm , uplo , diag , n , ap , work )

valzlantp ( norm , uplo , diag , n , ap , work )

Include Files

mkl.fi

Description

slantp dlantp clantp zlantp

The function ?lantp returns the value of the 1-norm, or the Frobenius norm, or the infinity norm, or the element of largest absolute value of a triangular matrix A , supplied in packed form.

Input Parameters

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 triangular. = ‘U’ : Upper triangular = ‘L’ : Lower triangular.
diag: CHARACTER*1 . Specifies whether or not the matrix A is unit triangular. = ‘N’ : Non-unit triangular = ‘U’ : Unit triangular.
n: INTEGER . The order of the matrix A . n≥ 0 . When n = 0 , ?lantp is set to zero.
ap: REAL for slantp DOUBLE PRECISION for dlantp COMPLEX for clantp DOUBLE COMPLEX for zlantp Array, DIMENSION ( n(n+1)/2 ). The upper or lower triangular matrix A , packed columnwise in a linear array. The j -th column of A is stored in the array ap as follows: if uplo = 'U' , AP(i + (j-1)j/2) =a(i,j) for 1≤ i≤ j ; if uplo = 'L' , ap(i + (j-1)(2n-j)/2) = a(i,j) for j≤ i≤ n . Note that when diag = 'U' , the elements of the array ap corresponding to the diagonal elements of the matrix A are not referenced, but are assumed to be one.
work: REAL for slantp and clantp . DOUBLE PRECISION for dlantp and zlantp . Workspace array, DIMENSION (max(1,lwork)) , where lwork≥n when norm = 'I' ; otherwise, work is not referenced.

Output Parameters

val: REAL for slantp / clantp . DOUBLE PRECISION for dlantp / zlantp . Value returned by the function.

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Developer Reference for Intel® oneAPI Math Kernel Library for Fortran

?lantp

Syntax

Include Files

Description

Input Parameters

Output Parameters