[octave] element by element operation

      plus       .+
      minus     .-
      times     .*
      rdivide   ./
      ldivide   .\
      power     .^  .**

https://www.gnu.org/software/octave/doc/v4.0.0/Arithmetic-Ops.html#Arithmetic-Ops

x .+ y

    Element-by-element addition. This operator is equivalent to +.


x = [1 2 3;
     4 5 6;
     7 8 9]

y = [1 1 1;
     1 1 1;
     1 1 1]

x.+y # equal x+y, because + originally is a element by element operator

ans =

    2    3    4
    5    6    7
    8    9   10



x .* y

    Element-by-element multiplication. If both operands are matrices, the number of rows and columns must both agree, or they must be broadcastable to the same shape.

x = [1 2 3;
     4 5 6;
     7 8 9]

y = [10 2 1;
     10 2 1;
     10 2 1]

x*y #normal *

ans =

    60    12     6
   150    30    15
   240    48    24

x.*y # element by element 1*10 4*10 7*10 .....
ans =

   10    4    3
   40   10    6
   70   16    9



x ./ y

    Element-by-element right division.



x = [1 2 3;
     4 5 6;
     7 8 9]

y = [10 2 1;
     10 2 1;
     10 2 1]

x./y
ans =

   0.10000   1.00000   3.00000
   0.40000   2.50000   6.00000
   0.70000   4.00000   9.00000




y = [10 2 1;
     10 2 1;
     10 2 1]
m=5
y./5 # equal y/5

ans =

   2.00000   0.40000   0.20000
   2.00000   0.40000   0.20000
   2.00000   0.40000   0.20000