drastic measures. One such measure would be to let each bit of the numbers stored in the array cells represent one graphics dot. This would increase the storage ability but tremendously complicate the programming.

For symmetric designs such as the circle, you can use a different measure. Take advantage of the symmetry to increase your output four-fold without increasing the size of the array one iota. How? By using the array to plot one-fourth of the circle in memory, then modifying the array three times to generate the remaining three parts (Fig- ure 13-6).

Figure 13-7. Divide and conquer

Try this out with the current program. Here are the changes you need to make to your current program in order to plot the lower-right corner :

30D=SQR(R^2+C^2)40 IF INT(D+.5)=20 THEN A(R,C)=1130 LPRINT CHR$(27)"*"CHR$(5)CHR$(N)CHR$(0);

By moving the center of the circle from (11,11) to (0,0) and increasing the radius from 10 to 20, you enlarge the figure.

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