?lansf

Developer Reference for Intel® oneAPI Math Kernel Library for Fortran

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ID 766686

Date 12/16/2022

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?lansf

Returns the value of the 1-norm, or the Frobenius norm, or the infinity norm, or the element of largest absolute value of a symmetric matrix in RFP format.

Syntax

val = slansf(norm, transr, uplo, n, a, work)

val = dlansf(norm, transr, uplo, n, a, work)

Include Files

mkl.fi

Description

The function ?lansf returns the value of the 1-norm, or the Frobenius norm, or the infinity norm, or the element of largest absolute value of an n-by-n real symmetric matrix A in the rectangular full packed (RFP) format .

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).

transr

CHARACTER*1.

Specifies whether the RFP format of matrix A is normal or transposed format.

If transr = 'N': RFP format is normal;

if transr = 'T': RFP format is transposed.

uplo

CHARACTER*1.

Specifies whether the RFP matrix A came from upper or lower triangular matrix.

If uplo = 'U': RFP matrix A came from an upper triangular matrix;

if uplo = 'L': RFP matrix A came from a lower triangular matrix.

n

INTEGER. The order of the matrix A. n≥ 0.

When n = 0, ?lansf is set to zero.

a

REAL for slansf

DOUBLE PRECISION for dlansf

Array, DIMENSION (n*(n+1)/2).

The upper (if uplo = 'U') or lower (if uplo = 'L') part of the symetric matrix A stored in RFP format.

work

REAL for slansf.

DOUBLE PRECISION for dlansf.

Workspace array, DIMENSION(max(1,lwork)), where

lwork≥n when norm = 'I' or '1' or 'O'; otherwise, work is not referenced.

Output Parameters

val

REAL for slansf

DOUBLE PRECISION for dlansf

Value returned by the function.

Parent topic: LAPACK Auxiliary Routines

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Developer Reference for Intel® oneAPI Math Kernel Library for Fortran

?lansf