r>%   (left, right, respectively) part of X.<br>%   Y = WKEEP(X,L,FIRST) returns the vector X(FIRST:FIRST+L-1).<br>%<br>%   Y = WKEEP(X,L) is equivalent to Y = WKEEP(X,L,'c').<br>%<br>%   For a matrix:<br>%   Y = WKEEP(X,S) extracts the central part of the matrix X. <br>%   S is the size of Y.<br>%   Y = WKEEP(X,S,[FIRSTR,FIRSTC]) extracts the submatrix of <br>%   matrix X, of size S and starting from X(FIRSTR,FIRSTC).
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