>> clear all
>> n=10^5;x=zeros(n,1);
>> n=10^9;x=zeros(n,1);
 ??? Error using ==> zeros
 Out of memory. Type HELP MEMORY for your options.

>> A=[2i 3 5; 7 -11i 13; 17 19 23]

A =
        0 + 2.0000i   3.0000             5.0000          
   7.0000                  0 -11.0000i  13.0000          
  17.0000            19.0000            23.0000          

>> A(1), A(3)
ans =

     0 + 2.0000i

ans =

    17

>> A(2,3)
ans =

    13

>> A'
ans =

        0 - 2.0000i   7.0000            17.0000          
   3.0000                  0 +11.0000i  19.0000          
   5.0000            13.0000            23.0000          


>> A(1:3,1)
ans =

        0 + 2.0000i
   7.0000          
  17.0000     

>> A(:,1)

ans =

        0 + 2.0000i
   7.0000          
  17.0000     

>> x=[ 1;2;3]

x =

     1
     2
     3

>> y=[1 2 3]

y =

     1     2     3

>> y'

ans =

     1
     2
     3

>> pi*x

ans =

    3.1416
    6.2832
    9.4248

>> y=y'

y =

     1
     2
     3

>> x'*y

ans =

    14

>> x,y,x'*y

x =

     1
     2
     3


y =

     1
     2
     3


ans =

    14

>> x = [1;1;1]
x =

     1
     1
     1

>>b=Ax
??? Undefined function or variable 'Ax'.
 
>> b = A*x

b =

   8.0000 + 2.0000i
  20.0000 -11.0000i
  59.0000        


>> for i=1:n
>> c=c+x(i)*y(i);
>> end
??? Undefined function or variable 'c'.

>> c=0;
>> for i=1:n
>> c=c+x(i)*y(i);
>> end
??? Index exceeds matrix dimensions.

>> n=3;
>> c=0;
>> for i=1:n
>> c=c+x(i)*y(i);
>> end
>> sizeof(x)
??? Undefined function or variable 'sizeof'.

>> size(x)

ans =

     3     1


>> help max

 MAX    Largest component.
    For vectors, MAX(X) is the largest element in X. For matrices,
    MAX(X) is a row vector containing the maximum element from each
    column. For N-D arrays, MAX(X) operates along the first
    non-singleton dimension.
 
    [Y,I] = MAX(X) returns the indices of the maximum values in vector I.
    If the values along the first non-singleton dimension contain more
    than one maximal element, the index of the first one is returned.
 
    MAX(X,Y) returns an array the same size as X and Y with the
    largest elements taken from X or Y.  Either one can be a scalar.
 
    [Y,I] = MAX(X,[],DIM) operates along the dimension DIM. 
 
    When complex, the magnitude MAX(ABS(X)) is used, and the angle
    ANGLE(X) is ignored.  NaN's are ignored when computing the maximum.
 
    Example: If X = [2 8 4   then max(X,[],1) is [7 8 9],
                     7 3 9]
 
        max(X,[],2) is [8    and max(X,5) is [5 8 5
                        9],                   7 5 9].
 
    See also MIN, MEDIAN, MEAN, SORT.

>> exit