Understand a part of code Detection CFAR

Hello everyone , i'm a beginner in matlab i need for a exam to understand a port of code ( the project its the detection CFAR )

i hope somoene can help me its very important for me <3

The following code is this part for generating a PFA :

I juste need to understand what do the " case " in the code

%=============================================== ================================================ =%
%======== Function that generates a PFA from a threshold T2Pfa = Gpfa ======%
%=============================================== ================================================ =%

% GOAL
% From a given threshold, a corresponding pfa is generated

% ENTRANCE
% T: threshold factor
% window: size of the observation window for the pfa estimation
% technical: method used to estimate the pfa of the signal

% EXIT
% Pfa: Probability of false alarm


function Pfa = Gpfa(T, window, technique)

% The following is used to ensure minimization
T(T <= 0) = realmin; %the smallest double-precision positive normalized floating-point number. This is equal to 2^(-1022)

n = window/2; % half window size
if ( n ~= round(window/2) ) % round(X) rounds each element of X to the nearest integer
  error('Window size must be an even number in CFAR')
end


% To process arrays of T, the following is used
orig_size = size(T); %size(A) returns a row vector whose elements are the lengths of the corresponding dimensions of T
T = T(:).'; % vector processing for internal sums to work, x(:) is exactly equivalent to reshape(x, [], 1)

switch upper(technical)
 
    case 'AC'
  % Except modified T
  Pfa = (1 + T).^(-window);
    case 'CAGO'
  % Note use of n = window/2;
  isum = repmat([0:n-1].',1,length(T)); %repmat(A,n) returns an array containing n copies of A in row and column dimensions. The size of B is size(A)*n when A is a matrix
  Tvec = repmat(T,n,1); %L = length(X) returns the length of the largest dimension of the array in X. For vectors, the length is simply the number of elements
  Pfa = 2 * (1 + T).^(-n) - 2 .* sum(bin(n + isum - 1, isum) .* (2 + Tvec).^ (-(n + isum)));
 
    case 'CASO'
  % Simplified Note use of n = window/2;
  isum = repmat([0:n-1].',1,length(T));
  Tvec = repmat(T,n,1);
  Pfa = 2 .* sum(bin(n + isum - 1, isum) .* (2 + Tvec).^ (-(n + isum)));

end

Pfa = reshape(Pfa,orig_size); %removes the effect of T(:).';

function val = bin(top, bot)

% internal binomial function
val = exp( gammaln(top + 1) - gammaln(bot + 1) - gammaln(top - bot + 1) );

Answer 1

[Walter Roberson]

switch upper(technical)
   case 'AC'

is like

if isequal(upper(technical), 'AC')

and the next case would be "elseif isequal..."

That is, the user is expected to pass in a character vector that is one of the three possibilities, in whatever case they want, and the code executes the appropriate section.