[MBDyn-users] Scalar function drive
Pierangelo Masarati
masarati at aero.polimi.it
Mon Feb 15 15:21:04 CET 2010
Romuald NORET wrote:
> Hello,
>
> I am trying to use scalar function drive (type multilinear), but something
> is wrong in my input file. To summarize, I would like to use a scalar
> function drive to define a coefficient (y) wihch depends of another (x):
> x y
> 1 0.5
> 10 0.7
> 100 1.0
> so I would like to use after "y(40)" which will return automatically
> "0.8", something like : "set: real MY_VALUE = MY_FUNCTION(40);"
> To define the driver, I wrote :
>
> scalar function:
> "MY_FUNCTION",
> multilinear,
> 1, 0.5,
> 10, 0.7,
> 100, 1.0;
>
> I read into input manual that the scalar function drive seems could do
> that, but I didn't find how to translate "MY_FUNCTION(40)" into MBDyn
> langage. I am sure it is very simple, but I didn't find how, could you
> give me a little bit of help?
set: real MY_VALUE = model::sf::MY_FUNCTION(40);
you can only use this after the <problem> block (e.g. after "end:
initial value;", as the model namespace needs to exist.
A minimal example is
<input>
begin: data;
end: data;
begin: initial value;
end: initial value;
scalar function:
"MY_FUNCTION",
multilinear,
1, 0.5,
10, 0.7,
100, 1.0;
remark: "evaluating MY_FUNCTION(40) yields", model::sf::MY_FUNCTION(40);
begin: control data;
end: control data;
</input>
$ mbdyn -f input
MBDyn - MultiBody Dynamics 1.X-Devel
compiled on Feb 13 2010 at 01:52:21
Copyright 1996-2010 (C) Paolo Mantegazza and Pierangelo Masarati,
Dipartimento di Ingegneria Aerospaziale <http://www.aero.polimi.it/>
Politecnico di Milano <http://www.polimi.it/>
MBDyn is free software, covered by the GNU General Public License,
and you are welcome to change it and/or distribute copies of it
under certain conditions. Use 'mbdyn --license' to see the conditions.
There is absolutely no warranty for MBDyn. Use "mbdyn --warranty"
for details.
reading from file "x"
Creating scalar solver with Umfpack linear solver
line 13, file <x>: evaluating MY_FUNCTION(40) yields, 0.8
warning, no dof owners are defined
MBDyn terminated normally
Cheers, p.
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