Start Matlab.  Wait for the > prompt.

type: x=2     (Assign the variable x the value 2)

type: 2=x     (It's the same mathematically, but to
               Matlab, this means give the number 2 the
               value x.  This is an error because the 
               value of the number 2 is not allowed to
               change.)
               
type: x=3;    (The semicolon suppresses the output ... )

type: x       ( ... but Matlab still does the operation.)

type: theta = x*x + x/(4+sqrt(x))
             
              (Variable names can be more than one letter.  
               Arithmetic in Matlab is similar to that on 
               a calculator: * means multiply, sqrt means
               take the square root, and so on.)
               
type: period = 2*pi

              (pi and e are built in with the right values.)
              
type: sin(theta)*sin(theta) + cos(theta)*cos(theta)

              (This is a trigonometric identy.  It seems fine, but)
              
type: sin(theta)*sin(theta) + cos(theta)*cos(theta) - 1

              (Computer computation is pretty accurate, but 
               not exact.)  
               
type: 1/sqrt(2) - sin(pi/4)

              (On my computer, this happened to come out exactly 
               right.  DON'T C OUNT ON IT.)
               
type: a(1) = 2
type: a(2) = 5
type: a(3) = 9

              (You are creating an "array".  Each time, it tells you
               the whole array, not just the number.  This is how
               Matlab handles vectors.  If you want a particular
               number, ask for it...)
               
type: a(2)    (The value of a(2) is 5, the value of a is [2,5,9].)

type: for i=1:6 

              (You get no prompt when you hit return because Matlab
               is waiting for more before it does anything.  You have 
               begun a "for loop".  Matlab will wait for you to tell it
               the whole loop before it does it.)
               
type: x = i*i (This is more information, but Matlab is still waiting.)

type: end     (This is how you tell Matlab the loop is finished.  Now
               Matlab will do the loop.  In this case, that means doing
               x = i*i over and over, with i having the values 
               1, 2, ... 6.)
               
type: for i=1:20

type: y = i - 1;

type: s(i) = y*i;

              (This time, the loop body has two statements, y=i*i-i and
               s(i) = y.  When the loop runs, these two statements
               will be "executed" for i = 1,2,3,...,20. ) 

type: end     (Because of the semicolons, it may seem that nothing has
               happened, but ... )
               
type: s       (The array s has been created and has 20 values.  For now,
               don't worry that Matlab calls these values "columns".)
               
type: plot(s) (Pictures are what life is about.)

type: help plot

              (Read the information and try to use some of it.)
              
type: help    (This is part of the reason Matlab is easy to learn.  
               Explore the help and tutorial facilities and you should
               be in good shape.)