Fix rounding in FFT (fixes #2961) (#2962)

leren1 · web-flow · commit fe61eb2bdf2b · 2022-03-05T19:16:34.000+02:00
diff --git a/src/main/java/com/thealgorithms/maths/FFT.java b/src/main/java/com/thealgorithms/maths/FFT.java
@@ -142,8 +142,10 @@ public double abs() {
          */
         public Complex divide(Complex z) {
             Complex temp = new Complex();
-            temp.real = (this.real * z.real + this.img * z.img) / (z.abs() * z.abs());
-            temp.img = (this.img * z.real - this.real * z.img) / (z.abs() * z.abs());
+            double d = z.abs() * z.abs();
+            d = (double)Math.round(d * 1000000000d) / 1000000000d;
+            temp.real = (this.real * z.real + this.img * z.img) / (d);
+            temp.img = (this.img * z.real - this.real * z.img) / (d);
             return temp;
         }
 
