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Invalid default value for property error in class properties

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Mathew
Mathew on 24 Apr 2020
Commented: Mathew on 24 Apr 2020
Greeting
I made a class and run dthe code in .m file
classdef myclass
properties (Constant)
a=physconst('LightSpeed');
b=a/2
end
end
it occurs error and says
Invalid default value for property 'b' in 'myclass':
Unrecognized function or variable 'a'.
physconst("LightSpeed") is a function in addon which name is 'Phased Array System Toolbox'
and its version is 4.3
a=physconst('LightSpeed')
b=a/2
I put thosdde two lines in command window
and it works fine...
so I have removed constant and tried to initialize them with class constructor
classdef myclass
properties
a;
b;
end
methods
function obj=myclass(obj)
a=physconst('LightSpeed');
b=a/2;
end
end
end
but the same error occured
I want to initialize my class property value with addon function but it have bring out error
How to deal with this error?

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Accepted Answer

per isakson
per isakson on 24 Apr 2020
Edited: per isakson on 24 Apr 2020
In the properties block one must refer to a as MyClass.a when Constant.
>> mc = MyClass
mc =
MyClass with properties:
a: 299792458
b: 149896229
>> which physconst -all
C:\Program Files\MATLAB\R2018b\toolbox\shared\siglib\physconst.m
>>
where
classdef MyClass
properties (Constant)
a = physconst('LightSpeed');
b = MyClass.a/2;
end
end
In your second class definition the constructor
function obj=myclass(obj)
a=physconst('LightSpeed');
b=a/2;
end
shall be
function obj=myclass()
obj.a = physconst('LightSpeed');
obj.b = obj.a /2;
end

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