.TH "slangb.f" 3 "Wed Oct 15 2014" "Version 3.4.2" "LAPACK" \" -*- nroff -*- .ad l .nh .SH NAME slangb.f \- .SH SYNOPSIS .br .PP .SS "Functions/Subroutines" .in +1c .ti -1c .RI "real function \fBslangb\fP (NORM, N, KL, KU, AB, LDAB, WORK)" .br .RI "\fI\fBSLANGB\fP returns the value of the 1-norm, Frobenius norm, infinity-norm, or the largest absolute value of any element of general band matrix\&. \fP" .in -1c .SH "Function/Subroutine Documentation" .PP .SS "real function slangb (characterNORM, integerN, integerKL, integerKU, real, dimension( ldab, * )AB, integerLDAB, real, dimension( * )WORK)" .PP \fBSLANGB\fP returns the value of the 1-norm, Frobenius norm, infinity-norm, or the largest absolute value of any element of general band matrix\&. .PP \fBPurpose: \fP .RS 4 .PP .nf SLANGB returns the value of the one norm, or the Frobenius norm, or the infinity norm, or the element of largest absolute value of an n by n band matrix A, with kl sub-diagonals and ku super-diagonals. .fi .PP .RE .PP \fBReturns:\fP .RS 4 SLANGB .PP .nf SLANGB = ( 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. .fi .PP .RE .PP \fBParameters:\fP .RS 4 \fINORM\fP .PP .nf NORM is CHARACTER*1 Specifies the value to be returned in SLANGB as described above. .fi .PP .br \fIN\fP .PP .nf N is INTEGER The order of the matrix A. N >= 0. When N = 0, SLANGB is set to zero. .fi .PP .br \fIKL\fP .PP .nf KL is INTEGER The number of sub-diagonals of the matrix A. KL >= 0. .fi .PP .br \fIKU\fP .PP .nf KU is INTEGER The number of super-diagonals of the matrix A. KU >= 0. .fi .PP .br \fIAB\fP .PP .nf AB is REAL array, dimension (LDAB,N) The band matrix A, stored in rows 1 to KL+KU+1. The j-th column of A is stored in the j-th column of the array AB as follows: AB(ku+1+i-j,j) = A(i,j) for max(1,j-ku)<=i<=min(n,j+kl). .fi .PP .br \fILDAB\fP .PP .nf LDAB is INTEGER The leading dimension of the array AB. LDAB >= KL+KU+1. .fi .PP .br \fIWORK\fP .PP .nf WORK is REAL array, dimension (MAX(1,LWORK)), where LWORK >= N when NORM = 'I'; otherwise, WORK is not referenced. .fi .PP .RE .PP \fBAuthor:\fP .RS 4 Univ\&. of Tennessee .PP Univ\&. of California Berkeley .PP Univ\&. of Colorado Denver .PP NAG Ltd\&. .RE .PP \fBDate:\fP .RS 4 September 2012 .RE .PP .PP Definition at line 124 of file slangb\&.f\&. .SH "Author" .PP Generated automatically by Doxygen for LAPACK from the source code\&.