direct: update birect.py

direct/birect.py

@@ -1,6 +1,7 @@
 #!/usr/bin/env python3
 # based on hamming_exact3.py, but with all debug stuff removed
 
+
 def birect(
     obj,
     lo,
@@ -297,9 +298,22 @@ def birect(
 
 
 if __name__ == "__main__":
-    from arsd_objectives import objective2210
     import numpy as np
 
+    def objective2210(x):
+        # another linear transformation of the rosenbrock banana function.
+        assert len(x) > 1, len(x)
+        a, b = x[:-1], x[1:]
+
+        a = a / 4.0 * 2 - 12 / 15
+        b = b / 1.5 * 2 - 43 / 15
+        # solution: 3.60      1.40
+
+        return (
+            np.sum(100 * np.square(np.square(a) + b) + np.square(a - 1))
+            / 499.0444444444444
+        )
+
     F = np.float64
     res = birect(
         lambda a: objective2210(np.array(a, F)),