Is it possible to multiply elements in a matrix greater than a certain value without using a loop?

For example is it possible to find all the values greater than 1 in matrix 1 and multiply all the values greater than 1 by 2, so that you get something like matrix 2 without using a loop? matrix1 = [1 2 3; 4 5 6; 7 8 9] matrix2 = [1 4 6; 8 10 12; 14 16 18]

Answer 1

[KSSV]

matrix1 = [1 2 3; 4 5 6; 7 8 9] ;

matrix2 = matrix1 ;

matrix2(matrix1>1) = matrix1(matrix1>1)*2 ;

matrix2 =

     1     4     6
     8    10    12
    14    16    18

[Wolfgang McCormack]

Hi, how can I ask MATLAB to only multiply the numbers greater than 1 in second column?

Answer 2

[Stephen23]

Method One: Simple exponent in just one line:

>> X = [1 2 3; 4 5 6; 7 8 9];
>> Y = X .* 2.^(X>1)
Y =
    1    4    6
    8   10   12
   14   16   18

Method Two: Indexing together with multiply:

>> idx = X>1;
>> Y = X;
>> Y(idx) = 2*X(idx)
  Y =
    1    4    6
    8   10   12
   14   16   18