circle.bas

100 REM DAVEVW.COM - CIRCLE
110 DEF FNAC(X)=2*ATN(SQR(1-X*X)/(1+X))
120 DIM DX(100)
130 FOR Y=0 TO 100
140 PRINT Y;CHR$(145)
150 A1=Y/100
160 DX(Y)=0:IF A1>-1 AND A1<=1 THEN DX(Y)=SIN(FNAC(A1))
170 NEXT Y
180 SP$="":FOR I=1 TO 255:SP$=SP$+" ":NEXT I
190 PRINT "      ";CHR$(145)
200 INPUT RX:RY=RX/2
210 IF RX<=0 OR RY<=0 OR RX >= 125 THEN STOP: GOTO 200
220 FOR Y=-RY TO RY
230 PRINT
240 X=INT(RX*DX(ABS(Y)/RY*100)+0.5)
250 PRINT MID$(SP$, 1, RX+1-X);
260 PRINT "*";
270 PRINT MID$(SP$, 1, X+X);
280 PRINT "*";
290 NEXT Y
300 GOTO 200