[ODE] ODE Message 2: vector has zero size (part 2)
DjArcas
djarcas at hotmail.com
Tue Jun 17 12:00:15 2003
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Having a look at odemath.cpp, I notice these comments on dNormalize3
// this may be called for vectors `a' with extremely small magnitude, fo
// example the result of a cross product on two nearly perpendicular =
vectors
// we must be robust to these small vectors. to prevent numerical error
// first find the component a[i] with the largest magnitude and then =
scal
// all the components by 1/a[i]. then we can compute the length of `a' =
an
// scale the components by 1/l. this has been verified to work with =
vector
// containing the smallest representable numbers.
Which is followed by a hefty function. My problems are occuring in =
dNormalize4 - which doesn't appear to have any of these clever extra =
checks. Could that be part of the problem?
Adam
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<DIV><FONT face=3DArial size=3D2>Having a look at odemath.cpp, I notice =
these=20
comments on dNormalize3</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV>
<P>// this may be called for vectors `a' with extremely small magnitude, =
fo</P>
<P>// example the result of a cross product on two nearly perpendicular=20
vectors</P>
<P>// we must be robust to these small vectors. to prevent numerical =
error</P>
<P>// first find the component a[i] with the largest magnitude and then =
scal</P>
<P>// all the components by 1/a[i]. then we can compute the length of =
`a' an</P>
<P>// scale the components by 1/l. this has been verified to work with=20
vector</P>
<P>// containing the smallest representable numbers.</P>
<P> </P>
<P><FONT face=3DArial size=3D2>Which is followed by a hefty function. My =
problems=20
are occuring in <FONT color=3D#808080>dNormalize4 - </FONT>which doesn't =
appear to=20
have any of these clever extra checks. Could that be part of the=20
problem?</FONT></P>
<P><FONT face=3DArial size=3D2></FONT> </P>
<P><FONT face=3DArial size=3D2>Adam</FONT></P></DIV></BODY></HTML>
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