dieter <[EMAIL PROTECTED]> writes:
> Adrian Pop <[EMAIL PROTECTED]> writes:
>
>> Hi Dieter,
>>
>> To ensure that we catch all the events at startup
>> the solver takes a very tiny step. We also save the
>> values of variables at time 0 to have them for pre(v).
>> I think this is the cause for double zero time, but
>> I'm not 100% sure.
>
> Neither am I 8-), the only thing I know is that in the case below it
> happens only when there is an if statement in the equation section,
> when you replace this line with the line below the fact does not
> happen.
By the way, I observed in another, related model when I'm using two "if
statements" in an equation section then I'm getting 3 zero time steps.
Dieter
>
> ------------------------------------------------------------
>
> connector Port
> Real pressure;
> flow Real flowrate;
> end Port;
>
> partial model TwoPorts
> Port inPort, outPort;
> equation
> inPort.flowrate + outPort.flowrate = 0;
> end TwoPorts;
>
> model Pipe
> extends TwoPorts;
> parameter Real a = .5;
> equation
> inPort.pressure = inPort.flowrate * a;
> end Pipe;
>
> model Pump
> extends TwoPorts;
> Real q;
> Real n( start=0);
> equation
> der( n) = 1;
> q = n - outPort.pressure;
> inPort.flowrate = if q > 0 then q else 0;
> // inPort.flowrate = q;
> end Pump;
>
> model Ambience
> Port port;
> equation
> port.pressure = 0;
> end Ambience;
>
> model Test
> Pump pu;
> Pipe pi;
> Ambience am1, am2;
> equation
> connect( am1.port, pu.inPort);
> connect( pu.outPort, pi.inPort);
> connect( pi.outPort, am2.port);
> end Test;
>
> // simulate( Test)
>
>>
>> Cheers,
>> Adrian Pop/
>>
>> dieter wrote:
>>> Hi,
>>>
>>> when I'm using the "time" variable with an "if" clause I'm getting
>>> strange date sets. All sets have two rows with zero time, as in the
>>> following:
>>>
>>> DataSet: time
>>> 0, 0
>>> 0, 0
>>> 2.220446049250313e-13, 2.220446049250313e-13
>>> 0.002, 0.002
>>> 0.004, 0.004
>>> 0.006, 0.006
>>> 0.008, 0.008
>>> 0.01, 0.01
>>> 0.012, 0.012
>>> ...
>>>
>>> DataSet: pi.inPort.pressure
>>> 0, 8.987170080912859e-71
>>> 0, 1.407479094429326e-112
>>> 2.220446049250313e-13, -1.002262231102861e-165
>>> 0.002, -3.504384971839359e-176
>>> 0.004, -5.630042739254032e-176
>>> 0.006, -7.755700506668704e-176
>>> ...
>>>
>>> it looks as if the *input* variable time has changed somehow!
>>> (I'm using svn:3603)
>>>
>>> Dieter
>>>
>>> ------------------------------------------------------------
>>>
>>> connector Port
>>> Real pressure;
>>> flow Real flowrate;
>>> end Port;
>>>
>>> // // record with innner/outer not possible // class Fluid
>>> "Water is the default" // parameter Real density = 1;
>>> // parameter Real viscosity = 1;
>>> // end Fluid;
>>>
>>> partial model TwoPorts
>>> // outer parameter Fluid fluid;
>>> Port inPort, outPort;
>>> equation
>>> inPort.flowrate + outPort.flowrate = 0;
>>> end TwoPorts;
>>>
>>> model Pipe
>>> extends TwoPorts;
>>> parameter Real a = .5;
>>> equation
>>> inPort.pressure = inPort.flowrate * a;
>>> end Pipe;
>>>
>>> model Pump
>>> extends TwoPorts;
>>> Real q;
>>> equation
>>> q = time - outPort.pressure - .1;
>>> inPort.flowrate = if q > 0 then q else 0;
>>> end Pump;
>>>
>>> model Ambience
>>> Port port;
>>> equation
>>> port.pressure = 0;
>>> end Ambience;
>>>
>>> model Test
>>> // inner parameter Fluid fluid;
>>> Pump pu;
>>> Pipe pi;
>>> Ambience am1, am2;
>>> equation
>>> connect( am1.port, pu.inPort);
>>> connect( pu.outPort, pi.inPort);
>>> connect( pi.outPort, am2.port);
>>> end Test;
>>>
>>> // simulate( Test)
>
--
Best wishes
H. Dieter Wilhelm
Darmstadt, Germany
