Hi,
I think matrix operator * is not correctly implemented in the single
precision case. I don't think my problem is only a numerical error linked
with floating point nature.
When I execute this octave script :
A = single([ 12545.125, 134587.125;
1247.12463378906, 63789.125])
B = single([ 12.2130002975464, 547854.8125;
4521.78955078125, 2145.14770507812])
C_single = single(A) * single(B)
C_double = double(A) * double(B)
C_double_2_2_calculated = C_double(2, 2)
C_single_2_2_calculated = C_single(2, 2)
C_double_2_2_theorical = double(A(2,1)) * double(B(1,2)) + double(A(2,2)) *
double(B(2,2))
C_single_2_2_theorical = single(A(2,1)) * single(B(1,2)) + single(A(2,2)) *
single(B(2,2))
I can see these results :
octave:9> script
A =
12545.125 134587.125
1247.12463378906 63789.125
B =
12.2130002975464 547854.8125
4521.78955078125 2145.14770507812
C_single =
608727872 7161616384
288456224 820080320
C_double =
608727869.110048 7161616366.99088
288456230.012003 820080327.51133
C_double_2_2_calculated = 820080327.51133
C_single_2_2_calculated = * 820080320*
C_double_2_2_theorical = 820080327.51133
C_single_2_2_theorical = * 820080384*
We can see there is no error with float64 numbers but it isn't the same case
with float32 using.
Last information, my octave version is the following :
octave:11> version
ans = 3.2.3
Best regards,
Nicolas from France
------------------------------------------------------------------------------
Start uncovering the many advantages of virtual appliances
and start using them to simplify application deployment and
accelerate your shift to cloud computing.
http://p.sf.net/sfu/novell-sfdev2dev
_______________________________________________
Octave-dev mailing list
[email protected]
https://lists.sourceforge.net/lists/listinfo/octave-dev
