how define in matlab like c++

hi i am new on matlab, i want to know who i define Constants like gravitation. in c++ it was super easy (define g=9.8) but in matlab i don't understand it.

[James Tursa]

If you mean something equivalent to the "const" keyword attribute for a variable, then no MATLAB does not have this capability for basic numeric variables.

Answer 1

[Fangjun Jiang]

even easier

>> g=9.8

g =

      9.8000

[nitzan netzer]

the problem is that i use in alot of function and i need to define it all over again every time. (i dont want to use a global becuse bad programming and slow)

[James Tursa]

@nitzan: This statement does not take much time in MATLAB and I wouldn't worry about it. In fact, later versions of MATLAB might even keep a reference copy of this in the background so that successive times you hit this line don't even allocate anything new ... you just get a reference to what was saved. Other parts of your code are very likely dominating your run time, so spend your effort improving that code instead of this line.

[Fangjun Jiang]

All true, @James Tursa!

If you insist, you can save the following two lines as G.m and include its folder location in your MATLAB path. Then you can use "G" whenever you want.

function out=G
out=9.8;

>> a=2*G

a =

     19.6000

[nitzan netzer]

ok,thank you very much for solution and fast answer very much. it's help me

[Walter Roberson]

See also https://www.mathworks.com/matlabcentral/answers/321973-how-to-have-presistent-physical-constants and https://www.mathworks.com/help/matlab/matlab_oop/properties-with-constant-values.html .

That is, you can create a class that has static methods that are defined as Constant. You can also create a package of functions that return constant values and import the package as needed.

Also https://www.mathworks.com/matlabcentral/mlc-downloads/downloads/submissions/34770/versions/1/previews/UserDefinedConstants/html/UserDefinedConstantsDemo.html