Developer Reference

  • 2021.1
  • 12/04/2020
  • Public Content
Contents

?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

float
LAPACKE_slantr
(
char
*
norm
,
char
*
uplo
,
char
*
diag
,
lapack_int
*
m
,
lapack_int
*
n
,
const
float
*
a
,
lapack_int
*
lda
,
float
*
work
);
double
LAPACKE_dlantr
(
char
*
norm
,
char
*
uplo
,
char
*
diag
,
lapack_int
*
m
,
lapack_int
*
n
,
const
double
*
a
,
lapack_int
*
lda
,
double
*
work
);
float
LAPACKE_clantr
(
char
*
norm
,
char
*
uplo
,
char
*
diag
,
lapack_int
*
m
,
lapack_int
*
n
,
const
lapack_complex_float
*
a
,
lapack_int
*
lda
,
float
*
work
);
double
LAPACKE_zlantr
(
char
*
norm
,
char
*
uplo
,
char
*
diag
,
lapack_int
*
m
,
lapack_int
*
n
,
const
lapack_complex_double
*
a
,
lapack_int
*
lda
,
double
*
work
);
Include Files
  • mkl.h
Description
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
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
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
.

Product and Performance Information

1

Performance varies by use, configuration and other factors. Learn more at www.Intel.com/PerformanceIndex.