Data commit

Task/Problem-of-Apollonius/F-Sharp/problem-of-apollonius.fs

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+type point = { x:float; y:float }
+type circle = { center: point; radius: float; }
+
+let new_circle x y r =
+   { center = { x=x; y=y }; radius = r }
+
+let print_circle c =
+   printfn "Circle(x=%.2f, y=%.2f, r=%.2f)"
+     c.center.x c.center.y c.radius
+
+let xyr c = c.center.x, c.center.y, c.radius
+
+let solve_apollonius c1 c2 c3
+                     s1 s2 s3 =
+
+   let x1, y1, r1 = xyr c1
+   let x2, y2, r2 = xyr c2
+   let x3, y3, r3 = xyr c3
+
+   let v11 = 2. * x2 - 2. * x1
+   let v12 = 2. * y2 - 2. * y1
+   let v13 = x1*x1 - x2*x2 + y1*y1 - y2*y2 - r1*r1 + r2*r2
+   let v14 = (2. * s2 * r2) - (2. * s1 * r1)
+
+   let v21 = 2. * x3 - 2. * x2
+   let v22 = 2. * y3 - 2. * y2
+   let v23 = x2*x2 - x3*x3 + y2*y2 - y3*y3 - r2*r2 + r3*r3
+   let v24 = (2. * s3 * r3) - (2. * s2 * r2)
+
+   let w12 = v12 / v11
+   let w13 = v13 / v11
+   let w14 = v14 / v11
+
+   let w22 = v22 / v21 - w12
+   let w23 = v23 / v21 - w13
+   let w24 = v24 / v21 - w14
+
+   let p = - w23 / w22
+   let q = w24 / w22
+   let m = - w12 * p - w13
+   let n = w14 - w12 * q
+
+   let a = n*n + q*q - 1.
+   let b = 2.*m*n - 2.*n*x1 + 2.*p*q - 2.*q*y1 + 2.*s1*r1
+   let c = x1*x1 + m*m - 2.*m*x1 + p*p + y1*y1 - 2.*p*y1 - r1*r1
+
+   let d = b * b - 4. * a * c
+   let rs = (- b - (sqrt d)) / (2. * a)
+
+   let xs = m + n * rs
+   let ys = p + q * rs
+
+   new_circle xs ys rs
+
+
+[<EntryPoint>]
+let main argv =
+  let c1 = new_circle 0. 0. 1.
+  let c2 = new_circle 4. 0. 1.
+  let c3 = new_circle 2. 4. 2.
+
+  let r1 = solve_apollonius c1 c2 c3 1. 1. 1.
+  print_circle r1
+
+  let r2 = solve_apollonius c1 c2 c3 (-1.) (-1.) (-1.)
+  print_circle r2
+  0