## Developer Reference

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

# ?lanst/?lanht

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 symmetric or complex Hermitian tridiagonal matrix.

## Syntax

Include Files
• mkl.fi
Description
The functions
?lanst
/
?lanht
return the value of the 1-norm, or the Frobenius norm, or the infinity norm, or the element of largest absolute value of a real symmetric or a complex Hermitian tridiagonal matrix
A
.
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).
n
INTEGER
. The order of the matrix
A
.
n
0
. When
n
= 0
,
?lanst
/
?lanht
is set to zero.
d
REAL
for
slanst
/
clanht
DOUBLE PRECISION
for
dlanst
/
zlanht
Array,
DIMENSION
(
n
). The diagonal elements of
A
.
e
REAL
for
slanst
DOUBLE PRECISION
for
dlanst
COMPLEX
for
clanht
DOUBLE COMPLEX
for
zlanht
Array,
DIMENSION
(
n
-1).
The (
n
-1) sub-diagonal or super-diagonal elements of
A
.
Output Parameters
val
REAL
for
slanst
/
clanht
DOUBLE PRECISION
for
dlanst
/
zlanht
Value returned by the function.