1 files changed, 43 insertions, 0 deletions
diff --git a/Master/Reference Architectures and Patterns/hjp5/examples/Listing1706.java b/Master/Reference Architectures and Patterns/hjp5/examples/Listing1706.java
new file mode 100644
index 0000000..4f1c41d
--- /dev/null
+++ b/Master/Reference Architectures and Patterns/hjp5/examples/Listing1706.java
@@ -0,0 +1,43 @@
+/* Listing1706.java */
+
+import java.math.*;
+
+public class Listing1706
+{
+  public static final BigDecimal ZERO = new BigDecimal("0");
+  public static final BigDecimal ONE  = new BigDecimal("1");
+  public static final BigDecimal TWO  = new BigDecimal("2");
+
+  public static BigDecimal sqrt(BigDecimal x, int digits)
+  {
+    BigDecimal zero = ZERO.setScale(digits + 10);
+    BigDecimal one  = ONE.setScale(digits + 10);
+    BigDecimal two  = TWO.setScale(digits + 10);
+    BigDecimal maxerr = one.movePointLeft(digits);
+    BigDecimal lower = zero;
+    BigDecimal upper = x.compareTo(one) <= 0 ? one : x;
+    BigDecimal mid;
+    while (true) {
+      mid = lower.add(upper).divide(two, BigDecimal.ROUND_HALF_UP);
+      BigDecimal sqr = mid.multiply(mid);
+      BigDecimal error = x.subtract(sqr).abs();
+      if (error.compareTo(maxerr) <= 0) {
+        break;
+      }
+      if (sqr.compareTo(x) < 0) {
+        lower = mid;
+      } else {
+        upper = mid;
+      }
+    }
+    return mid;
+  }
+
+  public static void main(String[] args)
+  {
+    BigDecimal sqrtTwo = sqrt(TWO, 100);
+    BigDecimal apxTwo  = sqrtTwo.multiply(sqrtTwo);
+    System.out.println("sqrt(2): " + sqrtTwo.toString());
+    System.out.println("check  : " + apxTwo.toString());
+  }
+}
+\ No newline at end of file