Wavelet Toolbox

wkeep

Keep part of a vector or a matrix

Syntax

• Y = wkeep(X,L,OPT)
  Y = wkeep(X,L)
  

Description

wkeep is a general utility.

For a vector, Y = wkeep(X,L,OPT) extracts the vector Y from the vector X. The length of Y is L.

If OPT = 'c' ('l', 'r', respectively), Y is the central (left, right, respectively) part of X.

Y = wkeep(X,L,FIRST) returns the vector X(FIRST:FIRST+L-1).

Y = wkeep(X,L) is equivalent to Y = wkeep(X,L,'c').

For a matrix, Y = wkeep(X,S) extracts the central part of the matrix X. The size of Y is S.

Y = wkeep(X,S,[FIRSTR FIRSTC]) extracts the submatrix of matrix X, of size S and starting from X(FIRSTR,FIRSTC).

Examples

• % For a vector. 
  x = 1:10;
  y = wkeep(x,6,'c')
  y =
      3     4     5     6     7     8
  
  y = wkeep(x,6)
  y =
      3     4     5     6     7     8
  
  y = wkeep(x,7,'c')
  y =
      2     3     4     5     6     7     8
  y = wkeep(x,6,'l')
  y =
      1     2     3     4     5     6
  
  y = wkeep(x,6,'r')
  y =
      5     6     7     8     9     10
  
  % For a matrix. 
  x = magic(5)
  x =
      17     24      1      8     15 
      23      5      7     14     16 
       4      6     13     20     22 
      10     12     19     21      3 
      11     18     25      2      9
  
  y = wkeep(x,[3 2])
  y =
      5     7
      6    13
     12    19
  

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