Introduction

The key format for your interaction with Maple is the statement.  You
type in statements for Maple; it evaluates them and gives you the
results. To let you know that it is waiting for input, Maple prints a
prompt:

>

For Maple to understand what you type, your commands must conform to
Maple's expectations for statements.  In particular, your statement must
be terminated by a semicolon (;) or a colon (:) for Maple to realize
that you have completed it.  The semicolon tells Maple to print out the
result of evaluating the statement, while the colon tells it not to
print the result.  The terminator does not need to be typed on the same
line as the rest of the statement, so if you forget it on one line you
can type it on the next line.  For example:

> 4+5: 

is a statement to add 4 and 5 but not to print the result.  An
equivalent statement is:

> 4+5 
> : 

In this case, after the first line Maple will assume that you have not
finished your statement.  On seeing the colon on the next line, Maple
will realize the statement is finished and evaluate 4+5.

You can put more than one statement on a line, just as you can break a
statement across multiple lines.  The requirement is that statements be
terminated, not that they fit on a line.

There are two Maple statements that do not have to be terminated in this way:

* The quit statement ends your Maple session.  This statement does not
require termination, so the following three command sequences all have
the same result (they return the output from the addition statement and
end the Maple session):

> 4+5;
> quit
9

> 4+5; quit
9

> 4+5; quit;
9

* The ? form of help request does not require termination. However, this
statement form must be on a line by itself and must not be embedded
within a statement.  The two following examples show mistaken use of the
form.

The first example produces a syntax error; the second example actually
works, but prints out the error message noted:

> 4+5: ?help 
syntax error:
4+5:?help
    ^
>

> 4+ 
> ?help 
  [a help window appears]
Error, invalid types in sum
> 

As shown above, when Maple detects a syntax error it echoes the
statement and shows you how far it was along in reading it when it
detected the error. It does this by placing a caret (^) below the point
in question.  The syntax error is generally somewhere in the statement
prior to this point.  The best way to recover from a syntax error is to
type a terminator (:, ;) and Return to ensure that Maple will know that
you are trying to enter in a new statement.  Then type in a corrected
version of the statement that gave you the syntax error.

Maple has a number of pre-defined global variables.  When you choose
names for your own variables, you should avoid the predefined ones. 
They are there to help you control how Maple works.  This is discussed
further in the section Some Predefined Symbols.