a = 0, b = 0, c != 0 - нет решений

levelp · May 23, 2015 · 4dae578 · 4dae578
1 parent 74f43e6
commit 4dae578
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diff --git a/src/main/java/QuadraticEquation.java b/src/main/java/QuadraticEquation.java
@@ -14,6 +14,8 @@ public class QuadraticEquation {
      */
     public static double[] solve(double a, double b, double c) {
         if (Math.abs(a) < EPS) {
+            if (Math.abs(b) < EPS)
+                return new double[]{};
             return new double[]{-c / b};
         }
         // Дискриминант

diff --git a/src/test/java/QuadraticEquationTest.java b/src/test/java/QuadraticEquationTest.java
@@ -52,4 +52,14 @@ public void testLinear() {
         assertArrayEquals("3x + 4 = 0", new double[]{-4 / 3.}, QuadraticEquation.solve(0, 3, 4), EPS);
         assertArrayEquals("1e-16*x^2 + x - 100 = 0", new double[]{100}, QuadraticEquation.solve(1e-16, 1, -100), EPS);
     }
+
+    /**
+     * a = 0, b = 0, c != 0 - нет решений
+     */
+    @Test
+    public void testABZeroNoRoots() {
+        assertArrayEquals("2 = 0", new double[]{}, QuadraticEquation.solve(0, 0, 2), EPS);
+        assertArrayEquals("4.5 = 0", new double[]{}, QuadraticEquation.solve(0, 0, 4.5), EPS);
+    }
+
 }