[Octave-bug-tracker] [bug #58944] [z, r, p]=qr(a, b) unexpectedly returns z as q instead of q' * b

[A.R. Burgers]

URL:
  <https://savannah.gnu.org/bugs/?58944>

                 Summary: [z,r,p]=qr(a,b) unexpectedly returns z as q instead
of q' * b
                 Project: GNU Octave
            Submitted by: arb
            Submitted on: Thu 13 Aug 2020 02:35:13 PM UTC
                Category: Octave Function
                Severity: 3 - Normal
                Priority: 5 - Normal
              Item Group: Incorrect Result
                  Status: None
             Assigned to: None
         Originator Name: 
        Originator Email: 
             Open/Closed: Open
                 Release: dev
         Discussion Lock: Any
        Operating System: Any

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Details:

according to the docs [z,r] = qr(a,b) returns the vector z=q'*b, where q is
the matrix returned by [q,r]=qr(a). This works as advertized, however [z,r,p]
= qr(a,b) unexpectedly (for me) returns z as the matrix q. This applies to all
of octave 5/6/7


ver = version
a = rand(3,2);
b = rand(3,1);
[z,r] = qr(a,b);
size_z_no_p_requested = size(z)
[z,r,p] = qr(a,b);
size_z_p_requested = size(z)



ver = 5.2.1
size_z_no_p_requested =
   3   1

size_z_p_requested =
   3   3





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