FOR FOR For Loop

Usage

The for loop executes a set of statements with an 
index variable looping through each element in a vector.
The syntax of a for loop is one of the following:

  for (variable=expression)
     statements
  end

Alternately, the parenthesis can be eliminated

  for variable=expression
     statements
  end

or alternately, the index variable can be pre-initialized
with the vector of values it is going to take:

  for variable
     statements
  end

The third form is essentially equivalent to for variable=variable,
where variable is both the index variable and the set of values
over which the for loop executes.  See the examples section for
an example of this form of the for loop.
