CS 100: Lecture L20

April 8

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A [ 1 2 3 4; 5 6 7 8; 9 10 11 12];
v = A(2,:)                           % Same as v = [ 5 6 7 8]
v = A(2,2:3)                         % Same as v = [6 7]
v = A(:,3)                           % Same as v = [3; 7; 11]
v = A(2:3,3)                         % Same as v = [7; 11]

x = [10 50 20 70 40 60]
v = x > 30                           % Same as v = [ 0 1 0 1 1 1]
u = find(v)                          % Same as u = [2 4 5 6]
y = (x< 15) | (x > 55)           % Same as y = [1 0 0 1 0 1]         


Java two-dimensional arrays

 

The array set-up

int[][] A = { {1,2,3},{4,5,6},{7,8,9},{10,11,12}};

is the same as

int[][] A = new int[4][3];
int k = 0;
for (int i=0;i< 4;i++)
{
   for (int j=0;j< 3;j++)
   {
      k++;
      A[i][j] = k;
   }
}