(global)

=

'L'

: apply

Q

or

Q

T

for real flavors (

Q

H

for complex flavors) from the left,

=

'R'

: apply

Q

or

Q

T

for real flavors (

Q

H

for complex flavors) from the right.

(global)

=

'N'

: apply

Q

(no transpose)

=

'T'

: apply

Q

T

(transpose, for real flavors)

=

'C'

: apply

Q

H

(conjugate transpose, for complex flavors)

(global)

The number of rows in the distributed matrix sub(

C

).

m

≥

0

.

(global)

The number of columns in the distributed matrix sub(

C

).

n

≥

0

.

(global)

The number of elementary reflectors whose product defines the matrix

Q

.

If

side

=

'L'

,

m

≥

k

≥

0

;

if

side

=

'R'

,

n

≥

k

≥

0

.

(local)

Pointer into the local memory to an array of size

lld_a

*

LOCc

(

ja

+

k

-1)

.

On entry, the

j

-th column

of the matrix stored in

a

must contain the vector that defines the elementary reflector

H

(

j

),

ja

≤

j

≤

ja

+

k

-1, as returned by

p?geqrf

in the

k

columns of its distributed matrix argument

A

(

ia

:*,

ja

:

ja

+

k

-1)

. The argument

A

(

ia

:*,

ja

:

ja

+

k

-1)

is modified by the

function

but restored on exit.

If

side

=

'L'

,

lld_a

≥

max(1,

LOCr

(

ia

+

m

-1))

,

if

side

=

'R'

,

lld_a

≥

max(1,

LOCr

(

ia

+

n

-1))

.

(global)

The row index in the global matrix

A

indicating the first row of sub(

A

).

(global)

The column index in the global matrix

A

indicating the first column of sub(

A

).

(global and local) array of size

dlen_

. The array descriptor for the distributed matrix

A

.

(local)

Array of size

LOCc

(

ja

+

k

-1)

.

tau

[

j

]

contains the scalar factor of the elementary reflector

H

(

j

+1),

j

= 0, 1, ...,

LOCc

(

ja

+

k

-1)

-1

, as returned by

p?geqrf

. This array is tied to the distributed matrix

A

.

(local)

Pointer into the local memory to an array of size

lld_c

*

LOCc

(

jc

+

n

-1)

.

On entry, the local pieces of the distributed matrix sub (

C

).

(global)

The row index in the global matrix

C

indicating the first row of sub(

C

).

(global)

The column index in the global matrix

C

indicating the first column of sub(

C

).

(global and local) array of size

dlen_

.

The array descriptor for the distributed matrix

C

.

(local)

Workspace array of size

lwork

.

(local or global)

The size of the array

work

.

lwork

is local input and must be at least

if

side

=

'L'

,

lwork

≥

mpc

0 + max(1,

nqc

0)

,

if

side

=

'R'

,

lwork

≥

nqc

0 + max(max(1,

mpc

0),

numroc

(

numroc

(

n

+

icoffc

,

nb_a

, 0, 0,

npcol

),

nb_a

, 0, 0,

lcmq

))

,

where

lcmq

=

lcm

/

npcol

,

lcm

=

iclm

(

nprow

,

npcol

)

,

iroffc

= mod(

ic-1

,

mb_c

)

,

icoffc

= mod(

jc-1

,

nb_c

)

,

icrow

=

indxg2p

(

ic

,

mb_c

,

myrow

,

rsrc_c

,

nprow

)

,

iccol

=

indxg2p

(

jc

,

nb_c

,

mycol

,

csrc_c

,

npcol

)

,

Mqc0

=

numroc

(

m

+

icoffc

,

nb_c

,

mycol

,

icrow

,

nprow

)

,

Npc0

=

numroc

(

n

+

iroffc

,

mb_c

,

myrow

,

iccol

,

npcol

)

,

ilcm

,

indxg2p

and

numroc

are ScaLAPACK tool functions;

myrow

,

mycol

,

nprow

, and

npcol

can be determined by calling the

function

blacs_gridinfo

.

If

lwork

= -1

, then

lwork

is global input and a workspace query is assumed; the

function

only calculates the minimum and optimal size for all work arrays. Each of these values is returned in the first entry of the corresponding work array, and no error message is issued by

pxerbla

.

On exit,

c

is overwritten by

Q

*sub(

C

), or

Q

T

*sub(

C

)/

Q

H

*sub(

C

), or sub(

C

)*

Q

, or sub(

C

)*

Q

T

/ sub(

C

)*

Q

H

On exit,

work

[0]

returns the minimal and optimal

lwork

.

(local)

= 0

: successful exit

< 0

: if the

i

-th argument is an array and the

j

-th entry

, indexed

j

-1,

had an illegal value,

then

info

= - (

i

*100 +

j

),

if the

i

-th argument is a scalar and had an illegal value,

then

info

= -

i

.