Provided by: liblapack-doc_3.3.1-1_all

**NAME**

LAPACK-3 - returns the value of the one norm, or the Frobenius norm, or the infinity norm, or the element of largest absolute value of a real symmetric matrix A, supplied in packed form

**SYNOPSIS**

REAL FUNCTION SLANSP( NORM, UPLO, N, AP, WORK ) CHARACTER NORM, UPLO INTEGER N REAL AP( * ), WORK( * )

**PURPOSE**

SLANSP returns the value of the one norm, or the Frobenius norm, or the infinity norm, or the element of largest absolute value of a real symmetric matrix A, supplied in packed form.

**DESCRIPTION**

SLANSP returns the value SLANSP = ( 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.

**ARGUMENTS**

NORM (input) CHARACTER*1 Specifies the value to be returned in SLANSP as described above. UPLO (input) CHARACTER*1 Specifies whether the upper or lower triangular part of the symmetric matrix A is supplied. = 'U': Upper triangular part of A is supplied = 'L': Lower triangular part of A is supplied N (input) INTEGER The order of the matrix A. N >= 0. When N = 0, SLANSP is set to zero. AP (input) REAL array, dimension (N*(N+1)/2) The upper or lower triangle of the symmetric 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. WORK (workspace) REAL array, dimension (MAX(1,LWORK)), where LWORK >= N when NORM = 'I' or '1' or 'O'; otherwise, WORK is not referenced. LAPACK auxiliary routine (version 3.2) April 2011 SLANSP(3lapack)