## Developer Reference

• 2020.2
• 07/15/2020
• Public Content
Contents

# ?lantp

Returns the value of the 1-norm, or the Frobenius norm, or the infinity norm, or the element of largest absolute value of a triangular matrix supplied in packed form.

## Syntax

Include Files
• mkl.fi
Description
The function
?lantp
returns the value of the 1-norm, or the Frobenius norm, or the infinity norm, or the element of largest absolute value of a triangular matrix
A
, supplied in packed form.
Input Parameters
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 triangular.
=
'U'
: Upper triangular
=
'L'
: Lower triangular.
diag
CHARACTER*1
.
Specifies whether or not the matrix
A
is unit triangular.
=
'N'
: Non-unit triangular
=
'U'
: Unit triangular.
n
INTEGER
. The order of the matrix
A
.
n
0
. When
n
= 0
,
?lantp
is set to zero.
ap
REAL
for
slantp
DOUBLE PRECISION
for
dlantp
COMPLEX
for
clantp
DOUBLE COMPLEX
for
zlantp
Array,
DIMENSION
(
n
(
n
+1)/2
).
The upper or lower triangular 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