Specify variable or constant parameter value
The ConstantValue property indicates whether
the value of a parameter can change during a simulation. Enter either true (value
is constant) or false (value can change).
You can allow the value of the parameter to change during a
simulation by specifying a rule that changes the Value property
of the parameter object.
The property ConstantValue is for parameter
objects; the property ConstantAmount is
for species objects.
As an example, consider feedback inhibition of an enzyme such as aspartate kinase by threonine. Aspartate kinase has three isozymes that are independently inhibited by the products of downstream reactions (threonine, homoserine, and lysine). Although threonine is made through a series of reactions in the synthesis pathway, for illustration, the reactions are simplified as follows:
To model inhibition of aspartate kinase by threonine, you could
use a rule like the algebraic rule below to vary
the rate of the above reaction and simulate inhibition. In the rule,
the rate constant for the above reaction is denoted by k_aspartate_kinase and
the quantity of threonine is threonine.
k_aspartate_kinase -(1/threonine)
| Applies to | Object: parameter |
| Data type | boolean |
| Data values | true or false. The default
value is 'true'. |
| Access | Read/write |
Create a model object.
modelObj = sbiomodel ('my_model');Add a parameter object.
parameterObj = addparameter (modelObj, 'kf');Change the ConstantValue property
of the parameter object from default (true) to false and
verify.
MATLAB® returns 1 for true and 0 for false.
set (parameterObj, 'ConstantValue', false); get(parameterObj, 'ConstantValue')
MATLAB returns:
ans =
0