Using a Variable between different functions
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Hello,
I have this two function. evAlice and evBob were defined in CHSH_ but I need to access themin basis function. But I could not know how can I access to evAlice and evBob in basis fucntion.
function [coin, I] = CHSH_(sigma_x,sigma_z)
ev1_of_alice = sigma_x;
ev2_of_alice = sigma_z;
ev1_of_bob = sigma_x+sigma_z;
ev2_of_bob = sigma_x-sigma_z;
evAlice=[sigma_x,sigma_z];
evBob=[sigma_x+sigma_z,sigma_x-sigma_z];
... %function is too long so I just put the relevant part
end
function [basis_mat] = basis(measurement_setting)
% Choose the correct basis depending on the
% measurement setting. If you change the observables,
% these are obtained by diagonalization
switch measurement_setting
case evAlice(0)
basis_mat = [1, 1; 1,-1]/sqrt(2);
case evAlice(1)
basis_mat = [1, 0; 0, 1];
case evBob(0)
basis_mat = [ 1+sqrt(2), 1-sqrt(2); 1, 1];
case evBob(1)
basis_mat = [-1-sqrt(2),-1+sqrt(2); 1, 1];
end
end
采纳的回答
the cyclist
2020-6-21
编辑：the cyclist
2020-6-21
You can pass them out of the first function:
function [coin, I, evAlice, evBob] = CHSH_(sigma_x,sigma_z)
and into the second one by calling it like this
basis(measurement_setting, evAlice, evBob)
and defining it as
function [basis_mat] = basis(measurement_setting, evAlice, evBob)
Alternatively, you could define those variables as global in scope, in both functions, but that is generally a bad idea.
4 个评论
Gözde Üstün
2020-6-21
the cyclist
2020-6-21
It's really up to you, based on what you think makes the code simpler and easier to understand in the long run.
You might want to google "global variable bad idea matlab" and do a little reading, before you decide. :-)
"Instad of that can I use global variable or is this better ?"
Global variables: slower, more buggy, harder to debug, obfuscate the code intent.
Input/output variables: faster, easier to debug, recommended by the MATLAB documentation as "best practice":
If you have lots of arguments then put them into a structure and pass that.
Gözde Üstün
2020-6-25
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