Developer Reference

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

?gbtrf

Computes the LU factorization of a general
m
-by-
n
band matrix.

Syntax

call sgbtrf
(
m
,
n
,
kl
,
ku
,
ab
,
ldab
,
ipiv
,
info
)
call dgbtrf
(
m
,
n
,
kl
,
ku
,
ab
,
ldab
,
ipiv
,
info
)
call cgbtrf
(
m
,
n
,
kl
,
ku
,
ab
,
ldab
,
ipiv
,
info
)
call zgbtrf
(
m
,
n
,
kl
,
ku
,
ab
,
ldab
,
ipiv
,
info
)
call gbtrf
(
ab
[
,
kl
]
[
,
m
]
[
,
ipiv
]
[
,
info
]
)
Include Files
  • mkl.fi
    ,
    lapack.f90
Description
The routine forms the
LU
factorization of a general
m
-by-
n
band matrix
A
with
kl
non-zero subdiagonals and
ku
non-zero superdiagonals, that is,
A
=
P*L*U
,
where
P
is a permutation matrix;
L
is lower triangular with unit diagonal elements and at most
kl
non-zero elements in each column;
U
is an upper triangular band matrix with
kl
+
ku
superdiagonals. The routine uses partial pivoting, with row interchanges (which creates the additional
kl
superdiagonals in
U
).
This routine supports the Progress Routine feature. See Progress Function for details.
Input Parameters
m
INTEGER
.
The number of rows in matrix
A
;
m
0.
n
INTEGER
.
The number of columns in matrix
A
;
n
0.
kl
INTEGER
.
The number of subdiagonals within the band of
A
;
kl
0.
ku
INTEGER
.
The number of superdiagonals within the band of
A
;
ku
0.
ab
REAL
for
sgbtrf
DOUBLE PRECISION
for
dgbtrf
COMPLEX
for
cgbtrf
DOUBLE COMPLEX
for
zgbtrf
.
Array, size
ldab
by *
.
The array
ab
contains the matrix
A
in band storage, in rows
kl
+ 1
to
2*
kl
+