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I like the events idea. I tried a slightly modified version, setting up
a species x that increases to 1 then decreases to zero; the parameter
xMax should increase to 1 then stay there.

I used the event
trigger: x > xMax
assignment: xMax = x
but it didn't seem to work (http://docs.u003f.com/max_model.xml) in
Copasi at least.

k

On 18/05/2011 16:55, Chris J. Myers wrote:
> Well, everything is implementation dependent :-).
>
> My assumption is that this would only be used in those cases where the
> assignment rule cycle reaches a fix point. Obviously, if it does not
> reach a fix point in a given time point, then it would cause the
> simulator to get stuck. In essence, you are defeating the check for
> cycles by going through an event. Therefore, buyer beware.
>
> Assuming that "x" and "xmax" are constant at a given time point, I
> don't see why this would not work for this case.
>
> Chris
>
> On May 18, 2011, at 9:47 AM, Sven Sahle wrote:
>
>> Hi Chris, Hi Michael,
>>
>> Am 18.05.2011 um 17:31 schrieb Chris J. Myers:
>>
>>> Rule:
>>> nextXmax := piecewise(x,gt(x,xmax),xmax)
>>>
>>> Event:
>>> Trigger: neq(xmax,nextXmax)
>>> Trigger initially true: false
>>> Assignment: xmax:=nextXmax
>>>
>>> I tried this, and it seems to work.
>>
>>
>> This is a clever idea, but wouldn't this mean the event is triggered
>> continuously if x is growing? This would mean that we would have to
>> trigger an infinite number of events and it is completely
>> implementation dependent how a solver would react to that.
>>
>> Sven
>>
>>
>> Dr. Sven Sahle
>> Abteilung Modellierung biologischer Prozesse
>> Universität Heidelberg, BIOQUANT/Zoologie
>>
>>
>>
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--
kieran smallbone
kieran.smallbone@manchester.ac.uk
http://u003f.com/

manchester centre for integrative systems biology
manchester interdisciplinary biocentre
131 princess street
manchester m1 7dn. uk
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