[quote author=Fu-Kwun Hwang link=topic=968.msg3593#msg3593 date=1234877938]
Sorry for the confusion: for dvx/dt=-k/m*x-b/m*vx; at evolution page
The left hand side means dx/dt , the variable at the left hand side means x.
And the variables at right hand side means: x,vx, k,b,m

What I means was that: you can not write the above equation as
dvx/dt=ax; //at [b]evolution[/b] page
and define ax=-k/m*x-b/m*vx; //at [b]fixed relation[/b] page
[/quote]

oic.... i understand this. use dvx/dt=-k/m*x-b/m*vx; at evolution page.

give Z-D time to understand this.

cheers!