# Maple Flow Control

We know what tools we need from the Matlab page. The difference between Matlab and Maple flow control is generally that Maple is a bit more verbose than Matlab.

## If

The basic syntax is

ifAs always, theconditionalthenstatement sequence; elifconditionalthenstatement sequence; elsestatement sequence; end if;

`elif`and

`else`are optional.

The conditionals have a similar form to those in other languages.
There are a few differences. First, conditionals in Maple do
not have a truth value outside of the "if" statement context.
In other words, the expression "5>2" has no truth value in Maple,
but `if 5>2 then c:=3; end if;` has meaning. If you want to find
the truth value of a conditional outside of an "if" statement,
you must use the `evalb` function. Here is an example.

5=3+2;
5 = 5
evalb(5=3+2);
*true*
if 5>2 then
x:=3;
elif 5=2 then
x:=103;
end if;
*x *:= 3

It is worth a special note that Maple uses := for the assignment operator, which frees up = to be used to test equality. This differs from many other languages, which typically use == for that purpose. A table summarizing logical operators follows.

Symbol | Meaning |
---|---|

= | Is Equal To |

<> | Is Not Equal To |

> | Is Greater Than |

>= | Is Greater Than Or Equal To |

< | Is Less Than |

<= | Is Less Than Or Equal To |

and | Logical And |

or | Logical Or |

## For

Maple has a for loop construction, just like every other language. The syntax is a bit different, however.forYou will find this to be fairly intuitive.variablefromexpressiontoexpressiondostatement sequenceend do;

for i from 1 to 10
x[i] := i:
end do;
y := 0:
for j from x[3] to x[3]^2 do
y := y+j:
end do;
the_answer_to_life_the_universe_and_everything:=y;
*the_answer_to_life_the_universe_and_everything*:=42

Note that the task of the first loop could have been done
more easily using

`x:=[seq(i,i=1..10)];`

Assignment 6 is posted.

The midterm exam will take place on Friday,
12 October. As always, you are permitted any paper
notes you find useful, but no electronic devices are
allowed. The test is cumulative, but emphasizes
the material covered in the last fours weeks.
A sample exam is
available.

You need to install
Matlab
on your computer by Wednesday.
You do not need Simulink or any particular toolboxes, though
you might find the Symbolic toolbox useful at some time
in the future (not in this class).