From the same London tiling shop as last month - more of the spectacular designs that people have chosen when tiling their kitchens, bathrooms, hallways or wherever!

(Sadly because of construction work on the new channel terminal this tile shop is now no more!)

Three more designs - which I invite you to reproduce using (elegant) LOGO procedures.

Alternatively, you might like to experiment with the following:

TO SQ :S
REPEAT 4 [FD :S RT 90]
END

TO PT :S :L
IF :S < :L [STOP]
SQ :S FD :S LT 45
PT :S/ SQRT (2) :L
PU RT 90
FD :S/SQRT (2)
PD
PT :S/ SQRT (2) :L
PU
BK :S/SQRT (2)
LT 45 PD BK :S
END

What is happening and what is its history

FIRST FORWARD

Beginners can start with FIRST FORWARD 1 to 9 here or go back and follow through the series month by month starting from the fIntroduction to LOGO in July 1999.

FIRST FORWARD 11

Summin' up

Last time you looked at several different sequences of number.

Now consider the following procedures.

TO SUMO :X :N
PR :X
WAIT 120
SUMO :X + :N :N + 2

END

1
2
5
10
17
26
37
50
65
82
101
122
stopped in
SUMO!!

What do you think is happening this time?

Try 'chasing' through the procedure the values: x = 1 and n = o.

No longer surprised!

 2
6
8
8
6
2
-4
-12
-22
-34
-48
stopped in
SUMO!!

Again why not experiment further by changing the value of the fourth line?

For example:

TO SUMO :X :N
PR :X
WAIT 120
SUMO :X + :N :N + 3
END

Or

SUMO :X * :N :N - 3
SUMO :X + :N * 2 :N + 1
SUMO :X - :N :N + 3

Etc

Any surprises?