From c5435604f6ca4774b729d2b209bc32df4420aa69 Mon Sep 17 00:00:00 2001
From: Michael Orlitzky <michael@orlitzky.com>
Date: Wed, 6 Mar 2013 20:05:09 -0500
Subject: [PATCH] Add powell(), powell1() and their tests.

---
 optimization/test_functions/powell.m  | 11 +++++++++++
 optimization/test_functions/powell1.m | 11 +++++++++++
 tests/powell1_tests.m                 | 16 ++++++++++++++++
 tests/powell_tests.m                  |  5 +++++
 4 files changed, 43 insertions(+)
 create mode 100644 optimization/test_functions/powell.m
 create mode 100644 optimization/test_functions/powell1.m
 create mode 100644 tests/powell1_tests.m
 create mode 100644 tests/powell_tests.m

diff --git a/optimization/test_functions/powell.m b/optimization/test_functions/powell.m
new file mode 100644
index 0000000..5031316
--- /dev/null
+++ b/optimization/test_functions/powell.m
@@ -0,0 +1,11 @@
+function f = powell(x1,x2,x3,x4)
+  ## The Powell function. See Dennis & Schnabel, Appendix B, problem
+  ## #1. (The "regular" Powell function is simply the Extended Powell
+  ## with m=1).
+  ##
+  ## This function has a minimum at x=(0,0,0,0) with f(x) == 0. The
+  ## suggested starting point is x0=(3,-1,0,1).
+  ##
+  f = (x1 + 10*x2)^2 + 5*(x3 - x4)^2;
+  f = f + (x2 - 2*x3)^4 + 10*(x1 - x4)^4;
+end
diff --git a/optimization/test_functions/powell1.m b/optimization/test_functions/powell1.m
new file mode 100644
index 0000000..b5e1771
--- /dev/null
+++ b/optimization/test_functions/powell1.m
@@ -0,0 +1,11 @@
+function f = powell1(x)
+  ##
+  ## A version of the Powell function which takes a column 4-vector as
+  ## an argument instead of four distinct arguments.
+  ##
+  if (length(x) == 4)
+    f = powell(x(1), x(2), x(3), x(4));
+  else
+    f = NA;
+  end
+end
diff --git a/tests/powell1_tests.m b/tests/powell1_tests.m
new file mode 100644
index 0000000..dbcf71e
--- /dev/null
+++ b/tests/powell1_tests.m
@@ -0,0 +1,16 @@
+## Test the optimal point.
+
+unit_test_equals("powell1([0;0;0;0]) == 0", ...
+		 0, ...
+		 powell1([0;0;0;0]));
+
+## It should fail with the wrong number of coordinates.
+f = powell1([1;2;3]);
+unit_test_equals("powell1 fails with too few coordinates", ...
+		 true, ...
+		 isna(f));
+
+f = powell1([1;2;3;4;5]);
+unit_test_equals("powell1 fails with too many coordinates", ...
+		 true, ...
+		 isna(f));
diff --git a/tests/powell_tests.m b/tests/powell_tests.m
new file mode 100644
index 0000000..3e56c92
--- /dev/null
+++ b/tests/powell_tests.m
@@ -0,0 +1,5 @@
+## Test the optimal point.
+
+unit_test_equals("powell(0,0,0,0) == 0", ...
+		 0, ...
+		 powell(0,0,0,0));
-- 
2.43.2