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WP34s: SLVQ implementation
Message #1 Posted by Dieter on 9 Oct 2011, 8:27 a.m.

I just noticed that SLVQ may return results with slight errors even in relatively simple cases:

  -1 ENTER
  -1 ENTER
   1 SLVQ
 
   WP34s results             correct (16 digits)
 
   0,61803 39887 49895 0     0,61803 39887 49894 8
   1,61803 39887 49894       1,61803 39887 49895
With 39 internal digits a correct 16-digit result should be no problem. So what's going on here?

Dieter

      
Re: WP34s: SLVQ implementation
Message #2 Posted by Marcus von Cube, Germany on 9 Oct 2011, 11:16 a.m.,
in response to message #1 by Dieter

If I'm not mistaken, SLVQ is not implemented natively but in user code (XROM). So the normal round-off errors may occur.

      
Re: WP34s: SLVQ implementation
Message #3 Posted by Paul Dale on 9 Oct 2011, 5:31 p.m.,
in response to message #1 by Dieter

Solve is a user code program so much work isn't carried out in high precision (some is still). It also searches at display accuracy (i.e. using the approximately equal test).

Thus, some lower order digits errors are to be expected.

- Pauli


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