AMSTRAD CPC464 User Manual page 109

This graphics demonstration plots a different coloured interference pattern:
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1 0 a $ = I N K E Y $ : R E M P R E S S A N Y K E Y T O
I N I T I A T E A N E W P A T T E R N S E Q U E N C E
2 0 I F a $ = " " T H E N 1 0
30 CLS
4 0 m = I N T ( R N D * 3 ) : R E M S E L E C T A R A N D O M
N U M B E R B E T W E E N 0 A N D 3
5 0 I F m > 2 T H E N T H E N 4 0 : R E M T R Y A G A I N
I F T H E V A L U E E X C E E D S 2
6 0 MODE m
7 0 i 1 = R N D * 2 6 : R E M S E L E C T R A N D O M I N K V A L U E S
8 0 i 2 = R N D * 2 6
9 0 I F A B S ( i 1-i 2 ) < 5 T H E N 70
1 0 0 I N K O , i 1 : I N K l , i 2
1 1 0 s = R N D * 5 + 3 s = RND*5+3
1 2 0 O R I G I N 3 2 0 ,-100
1 3 0 F O R x = -1 0 0 0 T O 0 S T E P S T E P s
1 4 0 M O V E 0 , 0
1 5 0 D R A W x , 3 0 0 : D R A W 0 , 6 0 0
1 6 0 M O V E 0 , 0
1 7 0 D R A W -x , 3 0 0 : D R A W 0 , 6 0 0
1 8 0 a $ = I N K E Y $
1 9 0 I F a $ < > " " T H E N T H E N 3 0 : R E M I N T E R R U P T
T H E L O O P B Y P R E S S I N G A N Y K E Y
2 0 0 N E X T x
2 1 0 G O T 0 1 0
This and the preceding program illustrate simple mathematical concepts in a colourful and very
visual way. Both are basically doing some sums on randomly generated ' seed' numbers to ensure
that each pattern is different in some way, and displaying the results as random lines.
Your CPC464 is excellent electronic graph paper, and one of the most classic geometrical patterns is
a sine wave:
1 0 R E M D R A W S I N E W A V E
2 0 M O D E 2
3 0 I N K 1 , 2 1
4 0 I N K 0 , 0
50 CLS
60 DEG
7 0 O R I G I N 0,200
8 0 F O R n = 0 T O 7 2 0
9 0 y = S I N ( n )
1 0 0 P L O T n * 64 0 / 7 2 0 , 1 9 8 * y , l
1 1 0 N E X T