Is there a way to get the pattern sequence form a generated graph?

The aim is to obtain a unique value (also know as the order in Shor's Algorithm) from the graph produced. The graph contains discrete values and depending on the parameters T and M, it will change. For example, the current parameters gives 4 different unique points before repeating it self (A pattern of repeating unique) I would like to know how I can obtain the no. of unique points it contains (not the each individual points values) from the graph. So from this graph I have attached, there is 4 unique points on the x-axis before repeating it self and I would like to know some lines of code that would give me the value 'N = 4' from the graph. If that makes sense?

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Code:

%% Only works for 4 orders properly!!

T = 7; % Seed

P = 128; %input("Please Enter the Bit size: "); % Bit 128, 256, 512, 1024

M = 100; %input('Please Enter the Number to be Factored: '); % Number to be factorized

t = sym(1):1:sym(P); % Signal duration/length

fncT = (T.^t) - floor(T.^t/M)*M; % Alternative version to mod(a,b)

% Fast fourier Transforms 1-D

% Rearranges 'fncT' by shifting the zero-frequency component to the centre of the array

FTsignal = fft(double(fncT) - mean(double(fncT)))/numel(double(fncT));

A = fftshift(FTsignal); % Computes duscrete fourier transform of A using fft algorithm

A_mag = abs(A.*A); % Returns absolute value of each element

% Plotting Different Graphs

title('Register in superposition state')

tiledlayout(4,1)

A_ax2 = nexttile; % Creates an axes object and inputs the graph into the next empty tile of the layout

plot(A_ax2,fncT)

xlim([0 P+1]) % Sets the x axis limit

ylabel('Amplitute')

A_ax3 = nexttile;

stem(A_ax3,fncT)

Answer 1

[Asvin Kumar]

Finding periodicity using autocorrelation seems like just the example for this scenario.