[Octave-bug-tracker] [bug #34173] Possible bug with multiplification with matrices and "-" sign

[Mikael]

Follow-up Comment #2, bug #34173 (project octave):

I saw that I forgot the error message.. 
Can't post all the code and all data sorry, but this is the basics:

[L,U,Pp,Qq,Rr]=lu(J);

Y = ... (a vector)
z1 = RrY;
z2 = L(Pp*z1);
z3 = Uz2;
dY =-(Qq*z3); (this is the step where it crashes)

without () 
dY =-Qq*z3;
the following message is posted
error: memory exhausted or requested size too large for range of Octave's
index type -- trying to return to prompt

I have a sparce matrix J (have a spy as attachment) tried to use just 
[L,U]=lu(J); 
Y = ...
dY=-U(LY);

this does not work good since octave gives
warning: matrix singular to machine precision, rcond = 1
warning: attempting to find minimum norm solution


(file #23907)
    _______________________________________________________

Additional Item Attachment:

File name: spy.jpg                        Size:15 KB


    _______________________________________________________

Reply to this item at:

  <http://savannah.gnu.org/bugs/?34173>

_______________________________________________
  Message sent via/by Savannah
  http://savannah.gnu.org/