프루버
10 !find_3_point_Circle
20 X1=1
30 Y1=1
40 X2=-1
50 Y2=-1
60 X3=-1
70 Y3=1
80 X12=X1-X2
90 X13=X1-X3
100 Y12=Y1-Y2
110 Y13=Y1-Y3
120 Y31=Y3-Y1
130 Y21=Y2-Y1
140 X31=X3-X1
150 X21=X2-X1
160 Sx13=X1*X1-X3*X3
170 Sy13=Y1*Y1-Y3*Y3
180 Sx21=X2*X2-X1*X1
190 Sy21=Y2*Y2-Y1*Y1
200 F=(Sx13*X12+Sy13*X12+Sx21*X13+Sy21*X13)/(2*(Y31*X12-Y21*X13))
210 G=(Sx13*Y12+Sy13*Y12+Sx21*Y13+Sy21*Y13)/(2*(X31*Y12-X21*Y13))
220 C=-X1*X1-Y1*Y1-2*G*X1-2*F*Y1
230 !! 원방정식 x^2 + y^2 + 2*g*x + 2*f*y + c = 0
240 !! 원중심이 h,k이고 반지름이 r이라면 원 방정식은 r^2=h^2+k^2-c
250 H=-G
260 K=-F
270 R=SQRT(H^2+K^2-C)
280 PRINT H,K,R
290 END