# plot a defined function

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reza hamzeh on 22 Oct 2019
Answered: Star Strider on 22 Oct 2019
hi people. i wrote two functions. they work correctly. now i want to plot the function N(T) versus T in range 0.1 to 14 . but i dont know how to do that.
maybe someone help me plz ?
clear;
function pa = partialtranspose(T)
J=1;B=4;d=4;
s0=[1 0;0 1];
sx=[0 1;1 0];
sy=[0 -1i;1i 0];
sz=[1 0;0 -1];
H = 2*J*kron(sz,sz)+B*(kron(sz,s0)+kron(s0,sz))+d*(kron(sx,sy)-kron(sy,sx));
ro = expm(-H/T)/trace(expm(-H/T));
pa = [ro(1,1) ro(2,1) ro(1,3) ro(2,3);ro(1,2) ro(2,2) ro(1,4) ro(2,4);
ro(3,1) ro(4,1) ro(3,3) ro(4,3);ro(3,2) ro(4,2) ro(3,4) ro(4,4)];
end
function ne = N(T)
ne=0.5*(sum(abs(eig(partialtranspose(T))))-1);
end

Star Strider on 22 Oct 2019
You can define ‘N’ as an anonymous function.
Try this:
N = @(T) 0.5*(sum(abs(eig(partialtranspose(T))))-1);
Tv = linspace(0.1, 14, 10); % Define Rnage Of ‘T’
for k = 1:numel(Tv)
Nv(k) = N(Tv(k));
end
figure
plot(Tv, Nv)
grid
I used the loop because ‘partialtranspose’ is not vectorised.

M on 22 Oct 2019
plot the function N(T) versus T in range 0.1 to 14
T is known ? T =[0.1 : 14 ] ?
And you want to plot ne(T) ?
In this case you could simply write
plot(T,ne)