dynamic & fixed

Asked by Alvin on 2011-12-01

hi all

what's the difference between "dynamic" and "fixed"
when I code " O.bodies.append(utils.box( center=(5.,5.,2.), extents=(2.,2.,2.),dynamic=True,fixed=False,wire=False))"

the DeprecationWarning: dynamic=True is deprecated, use fixed=False instead

Best regards

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Solved by:
Anton Gladky
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Best Anton Gladky (gladky-anton) said : #1

dynamic=True is deprecated

you have to remove this "dynamic" variable. You can use only fixed=True or fixed=False (default).

Jérôme Duriez (jduriez) said : #2

"dynamic" or "fixed" concern both the way changes in position of bodies (i.e. velocities) are handled by YADE.

- either velocities of bodies are updated according to sum of forces and newton's law : this concerns what was called previously "dynamic" bodies (for which dynamic = true)

- or velocities of bodies are considered to be constant (equal to an initial value set up by the user), whatever the sum of forces. Useful for boundaries bodies for example. They were called "non-dynamic" bodies => dynamic = false

These dynamic or non-dynamic designations were at one time replaced by the other terms of "fixed" (or not). So, there is no difference at all, except that "dynamic" concerns Yade's past, and that (dynamic = true) <=> (fixed = false). And the contrary.

So for your present Yade's use, listen to Anton's advice.

Alvin (lyj5300625) said : #3

Thanks Anton Gladky, that solved my question.

Alvin (lyj5300625) said : #4

thanks jduriez , that solved my question too.