Developer Reference for Intel® oneAPI Math Kernel Library for C
?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
floatLAPACKE_slantr ( char*norm , char*uplo , char*diag , lapack_int*m , lapack_int*n , constfloat*a , lapack_int*lda , float*work );
doubleLAPACKE_dlantr ( char*norm , char*uplo , char*diag , lapack_int*m , lapack_int*n , constdouble*a , lapack_int*lda , double*work );
floatLAPACKE_clantr ( char*norm , char*uplo , char*diag , lapack_int*m , lapack_int*n , constlapack_complex_float*a , lapack_int*lda , float*work );
doubleLAPACKE_zlantr ( char*norm , char*uplo , char*diag , lapack_int*m , lapack_int*n , constlapack_complex_double*a , lapack_int*lda , double*work );
Include Files
mkl.h
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
A <datatype> placeholder, if present, is used for the C interface data types in the C interface section above. See C Interface Conventions for the C interface principal conventions and type definitions.
norm
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
Specifies whether or not the matrix A has unit diagonal. = ‘N’ : Non-unit diagonal = ‘U’ : Unit diagonal.
m
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
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
The leading dimension of the array a .
lda≥ max(m,1) for column major layout and ≥ max(1, n ) for row major layout .
- 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.