?unmqr

Developer Reference for Intel® oneAPI Math Kernel Library for C

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ID 766684

Date 11/07/2023

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?unmqr

Multiplies a complex matrix by the unitary matrix Q of the QR factorization formed by ?geqrf.

Syntax

lapack_int LAPACKE_cunmqr (int matrix_layout, char side, char trans, lapack_int m, lapack_int n, lapack_int k, const lapack_complex_float* a, lapack_int lda, const lapack_complex_float* tau, lapack_complex_float* c, lapack_int ldc);

lapack_int LAPACKE_zunmqr (int matrix_layout, char side, char trans, lapack_int m, lapack_int n, lapack_int k, const lapack_complex_double* a, lapack_int lda, const lapack_complex_double* tau, lapack_complex_double* c, lapack_int ldc);

Include Files

mkl.h

Description

The routine multiplies a rectangular complex matrix C by Q or Q^H, where Q is the unitary matrix Q of the QR factorization formed by the routines ?geqrf or geqpf.

Depending on the parameters side and trans, the routine can form one of the matrix products Q*C, Q^H*C, C*Q, or C*Q^H (overwriting the result on C).

Input Parameters

matrix_layout

Specifies whether matrix storage layout is row major (LAPACK_ROW_MAJOR) or column major (LAPACK_COL_MAJOR).

side

Must be either 'L' or 'R'.

If side = 'L', Q or Q^H is applied to C from the left.

If side = 'R', Q or Q^H is applied to C from the right.

trans

Must be either 'N' or 'C'.

If trans = 'N', the routine multiplies C by Q.

If trans = 'C', the routine multiplies C by Q^H.

m

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

n

The number of columns in C (n≥ 0).

k

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

0 ≤k≤m if side = 'L';

0 ≤k≤n if side = 'R'.

a, c, tau

Arrays:

a size max(1, lda*k) for column major layout, max(1, lda*m) for row major layout when side ='L', and max(1, lda*n) for row major layout when side ='R' and tau are the arrays returned by cgeqrf / zgeqrf or cgeqpf / zgeqpf.

The size of tau must be at least max(1, k).

c(size max(1, ldc*n) for column major layout and max(1, ldc*m for row major layout) contains the m-by-n matrix C.

lda

The leading dimension of a. Constraints:

lda≥ max(1, m) for column major layout and lda≥ max(1, k) for row major layout if side = 'L';

lda≥ max(1, n) for column major layout and lda≥ max(1, k) for row major layout if side = 'R'.

ldc

The leading dimension of c. Constraint:

ldc≥ max(1, m) for column major layout and max(1, n) for row major layout.

Output Parameters

c: Overwritten by the product Q*C, Q^H*C, C*Q, or C*Q^H (as specified by side and trans).

Return Values

This function returns a value info.

If info=0, the execution is successful.

If info = -i, the i-th parameter had an illegal value.

Application Notes

The real counterpart of this routine is ormqr.

Parent topic: Orthogonal Factorizations: LAPACK Computational Routines

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Developer Reference for Intel® oneAPI Math Kernel Library for C

?unmqr

Syntax

Include Files

Description

Input Parameters

Output Parameters

Return Values

Application Notes