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Showing content from http://www.arrayfire.org/docs/grouplapackfactorfuncqr.htm below:

ArrayFire: qr

Perform QR decomposition. More...

AFAPI void qr (array &out, array &tau, const array &in) C++ Interface to perform QR decomposition in packed format. More...
AFAPI void qr (array &q, array &r, array &tau, const array &in) C++ Interface to perform QR decomposition. More...
AFAPI void qrInPlace (array &tau, array &in) C++ Interface to perform QR decomposition. More...
AFAPI af_err af_qr (af_array *q, af_array *r, af_array *tau, const af_array in) C Interface to perform QR decomposition. More...
AFAPI af_err af_qr_inplace (af_array *tau, af_array in) C Interface to perform QR decomposition. More...

Perform QR decomposition.

This function decomposes input matrix \(A\) into an orthogonal matrix \(Q\) and an upper triangular matrix \(R\) such that, \(A = Q * R\) and \(Q * Q^T = I\), where \(I\) is an identity matrix. The matrix \(Q\) is a square matrix of size \(max(M, N)\) where \(M\) and \(N\) are rows and columns of \(A\) respectively. The matrix \(R\) is the same size as \(A\).

This operation can be performed in ArrayFire using the following code snippet.

array q, r, tau;

qr(q, r, tau, in);

The additional parameter tau can be used to speed up solving over- and under-determined systems of equations.

The original matrix can be reconstructed using the following code snippet.

When memory is a concern, users can perform QR decomposition in place as shown below.

array out = in.copy();

array tau2;

qrInPlace(tau2, out);

◆ af_qr()

C Interface to perform QR decomposition.