[Octave-bug-tracker] [bug #56569] Inconsistent error with larger matrices

[anonymous]

URL:
  <https://savannah.gnu.org/bugs/?56569>

                 Summary: Inconsistent error with larger matrices
                 Project: GNU Octave
            Submitted by: None
            Submitted on: Mon 01 Jul 2019 01:59:24 PM UTC
                Category: Octave Function
                Severity: 3 - Normal
                Priority: 5 - Normal
              Item Group: Incorrect Result
                  Status: None
             Assigned to: None
         Originator Name: Mark van Rossum
        Originator Email: address@hidden
             Open/Closed: Open
         Discussion Lock: Any
                 Release: 4.4.1
        Operating System: GNU/Linux

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Details:

The script below calculates a simple matrix product
p=M.a

For the larger matrices the output fluctuates across the elements in vector
p.

Works fine on Matlab, and Octave 4.2.2 on another computer.

------
# this goes ok. All elements in the  vector p are the same.
N=100
M=50
m=ones(N,M);
a=ones(M,1);
p=m*a;
mean(p)
var(p) # should be zero

# this goes wrong. The elements in the  vector p vary.
N=1000
M=500
m=ones(N,M);
a=ones(M,1);
p=m*a;
mean(p)
var(p) # should be zero




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