Data commit

Task/Gaussian-elimination/Swift/gaussian-elimination.swift

@@ -0,0 +1,56 @@
+func gaussEliminate(_ sys: [[Double]]) -> [Double]? {
+  var system = sys
+
+  let size = system.count
+
+  for i in 0..<size-1 where system[i][i] != 0 {
+    for j in i..<size-1 {
+      let factor = system[j + 1][i] / system[i][i]
+
+      for k in i..<size+1 {
+        system[j + 1][k] -= factor * system[i][k]
+      }
+    }
+  }
+
+  for i in (1..<size).reversed() where system[i][i] != 0 {
+    for j in (1..<i+1).reversed() {
+      let factor = system[j - 1][i] / system[i][i]
+
+      for k in (0..<size+1).reversed() {
+        system[j - 1][k] -= factor * system[i][k]
+      }
+    }
+  }
+
+  var solutions = [Double]()
+
+  for i in 0..<size {
+    guard system[i][i] != 0 else {
+      return nil
+    }
+
+    system[i][size] /= system[i][i]
+    system[i][i] = 1
+    solutions.append(system[i][size])
+  }
+
+  return solutions
+}
+
+let sys = [
+  [1.00, 0.00, 0.00, 0.00, 0.00, 0.00, -0.01],
+  [1.00, 0.63, 0.39, 0.25, 0.16, 0.10, 0.61],
+  [1.00, 1.26, 1.58, 1.98, 2.49, 3.13, 0.91],
+  [1.00, 1.88, 3.55, 6.70, 12.62, 23.80, 0.99],
+  [1.00, 2.51, 6.32, 15.88, 39.90, 100.28, 0.60],
+  [1.00, 3.14, 9.87, 31.01, 97.41, 306.02, 0.02]
+]
+
+guard let sols = gaussEliminate(sys) else {
+  fatalError("No solutions")
+}
+
+for (i, f) in sols.enumerated() {
+  print("X\(i + 1) = \(f)")
+}