## Developer Reference

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

# ?lansf

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 in RFP format.

## Syntax

Include Files
• mkl.fi
Description
T
The function
?lansf
returns the value of the 1-norm, or the Frobenius norm, or the infinity norm, or the element of largest absolute value of an
n
-by-
n
real symmetric matrix
A
in the rectangular full packed (RFP) format .
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).
transr
CHARACTER*1
.
Specifies whether the RFP format of matrix
A
is normal or transposed format.
If
transr
=
'N'
: RFP format is normal;
if
transr
=
'T'
: RFP format is transposed.
uplo
CHARACTER*1
.
Specifies whether the RFP matrix
A
came from upper or lower triangular matrix.
If
uplo
=
'U'
: RFP matrix
A
came from an upper triangular matrix;
if
uplo
=
'L'
: RFP matrix
A
came from a lower triangular matrix.
n
INTEGER
. The order of the matrix
A
.
n
0.
When
n
= 0
,
?lansf
is set to zero.
a
REAL
for
slansf
DOUBLE PRECISION
for
dlansf
Array,
DIMENSION
(
n
*(
n
+1)/2).
The upper (if
uplo
=
'U'
) or lower (if
uplo
=
'L'
) part of the symetric matrix
A
stored in RFP format.
work
REAL
for
slansf
.
DOUBLE PRECISION
for
dlansf
.
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
slansf
DOUBLE PRECISION
for
dlansf
Value returned by the function.

#### Product and Performance Information

1

Intel's compilers may or may not optimize to the same degree for non-Intel microprocessors for optimizations that are not unique to Intel microprocessors. These optimizations include SSE2, SSE3, and SSSE3 instruction