1+5
ans =
     6
ans
ans =
     6
whos
  Name      Size                   Bytes  Class

  ans       1x1                        8  double array

Grand total is 1 element using 8 bytes

var1=5*pi+sin(0.5*pi)
var1 =
   16.7080
var2=-4;
whos
  Name       Size                   Bytes  Class

  ans        1x1                        8  double array
  var1       1x1                        8  double array
  var2       1x1                        8  double array

Grand total is 3 elements using 24 bytes

var3=var1/var2
var3 =
   -4.1770
whos
  Name       Size                   Bytes  Class

  ans        1x1                        8  double array
  var1       1x1                        8  double array
  var2       1x1                        8  double array
  var3       1x1                        8  double array

Grand total is 4 elements using 32 bytes

clear var1
whos
  Name       Size                   Bytes  Class

  ans        1x1                        8  double array
  var2       1x1                        8  double array
  var3       1x1                        8  double array

Grand total is 3 elements using 24 bytes

clear var*

whos
  Name      Size                   Bytes  Class

  ans       1x1                        8  double array

Grand total is 1 element using 8 bytes

arr1=[5 3 pi]
arr1 =
    5.0000    3.0000    3.1416
arr1(3)
ans =
    3.1416
whos
  Name       Size                   Bytes  Class

  ans        1x1                        8  double array
  arr1       1x3                       24  double array

Grand total is 4 elements using 32 bytes

arr1
arr1 =
    5.0000    3.0000    3.1416
arr2=arr1(1:2)
arr2 =
     5     3
whos
  Name       Size                   Bytes  Class

  ans        1x1                        8  double array
  arr1       1x3                       24  double array
  arr2       1x2                       16  double array

Grand total is 6 elements using 48 bytes

A=5:3
A =
   Empty matrix: 1-by-0
A=5:-1:3
A =
     5     4     3
I=[1,3]
I =
     1     3
A(I)
ans =
     5     3
A=10:10:100
A =
    10    20    30    40    50    60    70    80    90   100
A=[10:10:100]
A =
    10    20    30    40    50    60    70    80    90   100
A=[10:10:100, 100:-10:10]
A =
  Columns 1 through 13 
    10    20    30    40    50    60    70    80    90   100   100    90    80
  Columns 14 through 20 
    70    60    50    40    30    20    10
A=[10:10:100]
A =
    10    20    30    40    50    60    70    80    90   100
I=1:2:9
I =
     1     3     5     7     9
J=2:2:10
J =
     2     4     6     8    10
A(I)=A(J)
A =
    20    20    40    40    60    60    80    80   100   100
A(1)=10
A =
    10    20    40    40    60    60    80    80   100   100
I=[I,3]
I =
     1     3     5     7     9     3
A(I)=A(J)
???  In an assignment  A(I) = B, the number of elements in B and
 I must be the same.

help sum

 SUM Sum of elements.
    For vectors, SUM(X) is the sum of the elements of X. For
    matrices, SUM(X) is a row vector with the sum over each
    column. For N-D arrays, SUM(X) operates along the first
    non-singleton dimension.
 
    SUM(X,DIM) sums along the dimension DIM. 
 
    Example: If X = [0 1 2
                     3 4 5]
 
    then sum(X,1) is [3 5 7] and sum(X,2) is [ 3
                                              12];
 
    See also PROD, CUMSUM, DIFF.

 Overloaded methods
    help sym/sum.m

exit