Epson FX Circle Plotting, 30D=SQR((R-11)^2+(C-11^2), 20 FOR R=1 TO N: FOR C=1 TO N, 40 IF INT(D+.S)=10 THEN A(R,C)=1, Figure 13-5. Plotting a circle

Figure 13-5.Plotting a circleCircle Plotting

You can have your program examine the cells of an array in any order; the following program scans them row by row, using two loops:

20 FOR R=1 TO N: FOR C=1 TO N

At each cell, line 30 calculates the cell’s distance from a center point by using the distance formula:

30D=SQR((R-11)^2+(C-11^2)

Next the program compares this distance with a number (10) that specifies the radius of a circle. Notice that this formula commonly results in a number that includes a decimal fraction, e.g., 8.94.

If the distance for the current cell A(R,C) is close to 10, you set its contents equal to one: otherwise, you leave it alone.

40 IF INT(D+.S)=10 THEN A(R,C)=1

Line 40 sets any cell whose distance is between 9.5 and 10.5 equal to one.

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