## Developer Reference

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

# ?lansp

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

## Syntax

Include Files
• mkl.fi
Description
The function
?lansp
returns the value of the 1-norm, or the Frobenius norm, or the infinity norm, or the element of largest absolute value of a real/complex symmetric 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
i
j
)), 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 upper or lower triangular part of the symmetric matrix
A
is supplied.
If
uplo
=
'U'
: Upper triangular part of
A
is supplied
If
uplo
=
'L'
: Lower triangular part of
A
is supplied.
n
INTEGER
. The order of the matrix
A
.
n
0
. When
n
= 0
,
?lansp
is set to zero.
ap
REAL
for
slansp
DOUBLE PRECISION
for
dlansp
COMPLEX
for
clansp
DOUBLE COMPLEX
for
zlansp
Array,
DIMENSION
(
n
(
n
+1)/2
).
The upper or lower triangle of the symmetric 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
1 ≤
i
j
;
if
uplo
=
'L'
,
ap
(
i
+ (
j
-1)(2
n
-
j
)/2) =
A
(
i
,
j
)
for
j
i
n
.
work
REAL
for
slansp
and
clansp
.
DOUBLE PRECISION
for
dlansp
and
zlansp
.
Workspace array,
DIMENSION
(max(1,
lwork
))
, where
lwork
n
when
norm
=
'I'
or
'1'
or
'O'
; otherwise,
work
is not referenced.
Output Parameters
val
REAL
for
slansp
/
clansp
DOUBLE PRECISION
for
dlansp
/
zlansp
Value returned by the function.