## Developer Reference

• 2020.2
• 07/15/2020
• 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

Include Files
• mkl.fi
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
The data types are given for the Fortran interface.
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).
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
CHARACTER*1
.
Specifies whether or not the matrix
A
has unit diagonal.
=
'N'
: Non-unit diagonal
=
'U'
: Unit diagonal.
m
INTEGER
.
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
INTEGER
.
The number of columns of the matrix
A
.
n
0
, and if
uplo
=
'L'
,
n
m
.
When