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Help on FOR from MATLAB
The following MATERIAL is copied DIRECTLY from MATLAB is completely
the property of MATHWORKS. I have given links to where you will find
the following help.
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>> help for

 FOR    Repeat statements a specific number of times.
    The general form of a FOR statement is:
  
       FOR variable = expr, statement, ..., statement END
  
    The columns of the expression are stored one at a time in
    the variable and then the following statements, up to the
    END, are executed. The expression is often of the form X:Y,
    in which case its columns are simply scalars. Some examples
    (assume N has already been assigned a value).
  
         FOR I = 1:N,
             FOR J = 1:N,
                 A(I,J) = 1/(I+J-1);
             END
         END
  
    FOR S = 1.0: -0.1: 0.0, END steps S with increments of -0.1
    FOR E = EYE(N), ... END  sets E to the unit N-vectors.
 
    Long loops are more memory efficient when the colon expression appears
    in the FOR statement since the index vector is never created.
 
    The BREAK statement can be used to terminate the loop prematurely.
 
    See also IF, WHILE, SWITCH, BREAK, END.
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From MATLAB->Getting Started->Programming with MATLAB->for

for
The for loop repeats a group of statements a fixed, predetermined
number of times. A matching end delineates the statements.

       for n = 3:32
          r(n) = rank(magic(n));
       end
       r

The semicolon terminating the inner statement suppresses repeated
printing, and the r after the loop displays the final result.

It is a good idea to indent the loops for readability, especially when
they are nested.

       for i = 1:m
          for j = 1:n
	      H(i,j) = 1/(i+j);
          end
       end
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From MATLAB->Using MATLAB->M-File Programming->
Programming and Data Types: M-File Programming: for

for
The for loop executes a statement or group of statements a
predetermined number of times. Its syntax is:

    for index = start:increment:end
         statements
    end

The default increment is 1. You can specify any increment, including a
negative one. For positive indices, execution terminates when the
value of the index exceeds the end value; for negative increments, it
terminates when the index is less than the end value.

For example, this loop executes five times.

    for i = 2:6
	x(i) = 2*x(i-1);
    end

You can nest multiple for loops.

    for i = 1:m
	for j = 1:n
	    A(i,j) = 1/(i + j - 1);
        end
    end

Note    You can often speed up the execution of MATLAB code by
replacing for and while loops with vectorized code. See "Vectorization
of Loops" on page 1-91 for details.

Using Arrays as Indices
The index of a for loop can be an array. For example, consider an
m-by-n array A. The statement

    for i = A
       statements
    end

sets i equal to the vector A(:,k). For the first loop iteration, k is
equal to 1; for the second k is equal to 2, and so on until k equals
n. That is, the loop iterates for a number of times equal to the
number of columns in A. For each iteration, i is a vector containing
one of the columns of A.
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MATLAB Function Reference: for

for

Repeat statements a specific number of times

Syntax
for variable = expression
    statements
end

Description
The general format is

for variable = expression
    statement
    ...
    statement
end

The columns of the expression are stored one at a time in the variable
while the following statements, up to the end, are executed.

In practice, the expression is almost always of the form scalar :
scalar, in which case its columns are simply scalars.

The scope of the for statement is always terminated with a matching end.

Examples
Assume n has already been assigned a value. Create the Hilbert matrix,
using zeros to preallocate the matrix to conserve memory:

a = zeros(n,n)  % Preallocate matrix
for i = 1:n
    for j = 1:n
        a(i,j) = 1/(i+j -1);
    end
end
Step s with increments of -0.1

for s = 1.0: -0.1: 0.0,..., end
Successively set e to the unit n-vectors:

for e = eye(n),..., end
The line

for V = A,..., end
has the same effect as

for j = 1:n, V = A(:,j);..., end
except j is also set here.

See Also
break, end, if, return, switch, while

The colon operator :
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