p?ormr2/p?unmr2

Developer Reference for Intel® oneAPI Math Kernel Library for Fortran

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ID 766686

Date 3/22/2024

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p?ormr2/p?unmr2

Multiplies a general matrix by the orthogonal/unitary matrix from an RQ factorization determined by p?gerqf (unblocked algorithm).

Syntax

call psormr2(side, trans, m, n, k, a, ia, ja, desca, tau, c, ic, jc, descc, work, lwork, info)

call pdormr2(side, trans, m, n, k, a, ia, ja, desca, tau, c, ic, jc, descc, work, lwork, info)

call pcunmr2(side, trans, m, n, k, a, ia, ja, desca, tau, c, ic, jc, descc, work, lwork, info)

call pzunmr2(side, trans, m, n, k, a, ia, ja, desca, tau, c, ic, jc, descc, work, lwork, info)

Description

The p?ormr2/p?unmr2routine overwrites the general real/complex m-by-n distributed matrix sub (C)=C(ic:ic+m-1, jc:jc+n-1) with

Q*sub(C) if side = 'L' and trans = 'N', or

Q^T*sub(C) / Q^H*sub(C) if side = 'L' and trans = 'T' (for real flavors) or trans = 'C' (for complex flavors), or

sub(C)*Q if side = 'R' and trans = 'N', or

sub(C)*Q^T / sub(C)*Q^H if side = 'R' and trans = 'T' (for real flavors) or trans = 'C' (for complex flavors).

where Q is a real orthogonal or complex unitary distributed matrix defined as the product of k elementary reflectors

Q = H(1)*H(2)*...*H(k) (for real flavors)

Q = (H(1))^H*(H(2))^H*...*(H(k))^H (for complex flavors)

as returned by p?gerqf . Q is of order m if side = 'L' and of order n if side = 'R'.

Input Parameters

side

(global) CHARACTER.

= '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.

trans

(global) CHARACTER.

= 'N': apply Q (no transpose)

= 'T': apply Q^T (transpose, for real flavors)

= 'C': apply Q^H(conjugate transpose, for complex flavors)

m

(global) INTEGER.

The number of rows in the distributed matrix sub(C). m ≥ 0.

n

(global) INTEGER.

The number of columns in the distributed matrix sub(C). n ≥ 0.

k

(global) INTEGER.

The number of elementary reflectors whose product defines the matrix Q.

If side = 'L', m ≥ k ≥ 0;

if side = 'R', n ≥ k ≥ 0.

a

(local)

REAL for psormr2

DOUBLE PRECISION for pdormr2

COMPLEX for pcunmr2

COMPLEX*16 for pzunmr2.

Pointer into the local memory to an array of size

(lld_a, LOCc(ja+m-1)) if side='L',

(lld_a, LOCc(ja+n-1)) if side='R',

where lld_a ≥ max (1, LOCr(ia+k-1)).

On entry, the i-th row must contain the vector that defines the elementary reflector H(i), ia ≤ i ≤ ia+k-1, as returned by p?gerqf in the k rows of its distributed matrix argument A(ia:ia+k-1, ja:*).

The argument A(ia:ia+k-1, ja:*) is modified by the routine but restored on exit.

ia

(global) INTEGER.

The row index in the global matrix A indicating the first row of sub(A).

ja

(global) INTEGER.

The column index in the global matrix A indicating the first column of sub(A).

desca

(global and local) INTEGER array of size dlen_. The array descriptor for the distributed matrix A.

tau

(local)

REAL for psormr2

DOUBLE PRECISION for pdormr2

COMPLEX for pcunmr2

COMPLEX*16 for pzunmr2.

Array of size LOCc(ia+k-1). tau(j) contains the scalar factor of the elementary reflector H(j), as returned by p?gerqf. This array is tied to the distributed matrix A.

c

(local)

REAL for psormr2

DOUBLE PRECISION for pdormr2

COMPLEX for pcunmr2

COMPLEX*16 for pzunmr2.

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).

ic

(global) INTEGER.

The row index in the global matrix C indicating the first row of sub(C).

jc

(global) INTEGER.

The column index in the global matrix C indicating the first column of sub(C).

descc

(global and local) INTEGER array of size dlen_. The array descriptor for the distributed matrix C.

work

(local)

REAL for psormr2

DOUBLE PRECISION for pdormr2

COMPLEX for pcunmr2

COMPLEX*16 for pzunmr2.

Workspace array of size lwork.

lwork

(local or global) INTEGER.

The size of the array work.

lwork is local input and must be at least

if side = 'L', lwork ≥ mpc0 + max(max(1, nqc0), numroc(numroc(m+iroffc, mb_a, 0, 0, nprow), mb_a, 0, 0, lcmp)),

if side = 'R', lwork ≥ nqc0 + max(1, mpc0),

where lcmp = lcm/nprow,

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),

Mpc0 = numroc(m+iroffc, mb_c, myrow, icrow, nprow),

Nqc0 = numroc(n+icoffc, nb_c, mycol, iccol, npcol),

ilcm, indxg2p and numroc are ScaLAPACK tool functions; myrow, mycol, nprow, and npcol can be determined by calling the subroutine blacs_gridinfo.

If lwork = -1, then lwork is global input and a workspace query is assumed; the routine 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.

Output Parameters

c

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

work

On exit, work(1) returns the minimal and optimal lwork.

info

(local) INTEGER.

= 0: successful exit

< 0: if the i-th argument is an array and the j-th entry 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.

NOTE:

The distributed submatrices A(ia:*, ja:*) and C(ic:ic+m-1,jc:jc+n-1) must verify some alignment properties, namely the following expressions should be true:

If side = 'L', ( nb_a.eq.mb_c .AND. icoffa.eq.iroffc ).

If side = 'R', ( nb_a.eq.nb_c .AND. icoffa.eq.icoffc .AND. iacol.eq.iccol ).

Parent topic: ScaLAPACK Auxiliary Routines

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Developer Reference for Intel® oneAPI Math Kernel Library for Fortran

p?ormr2/p?unmr2

Syntax

Description

Input Parameters

Output Parameters

See Also