### magma_dgeqrf documentation

Posted:

**Tue Jul 10, 2012 5:41 am**Hello again,

It looks like the documentation magma_dgeqrf functions is not up-to-date:
It seems that the upper part of the matrix isn't R contrary to what is stated in the documentation.

magma_dgeqrf3 documentation has the same kind of issue but it has a correct description:

Regards,

RĂ©mi

It looks like the documentation magma_dgeqrf functions is not up-to-date:

Code: Select all

```
A (input/output) DOUBLE_PRECISION array on the GPU, dimension (LDDA,N)
On entry, the M-by-N matrix A.
On exit, the elements on and above the diagonal of the array
contain the min(M,N)-by-N upper trapezoidal matrix R (R is
upper triangular if m >= n); the elements below the diagonal,
with the array TAU, represent the orthogonal matrix Q as a
product of min(m,n) elementary reflectors (see Further
Details).
```

magma_dgeqrf3 documentation has the same kind of issue but it has a correct description:

The issue is of course not major but I prefer to report it if someone else wonders why he doesn't get R as expected.DGEQRF3 computes a QR factorization of a DOUBLE_PRECISION M-by-N matrix A:

A = Q * R. This version stores the triangular matrices T used in

the block QR factorization so that Q can be applied directly (i.e.,

without being recomputed) later. As a result, the application

of Q is much faster. The upper triangular matrices for V have 0s

in them and the corresponding parts of theupper triangular R are.

stored separately

Regards,

RĂ©mi