From: Michael Orlitzky <michael@orlitzky.com>
Date: Mon, 17 Dec 2012 15:19:15 +0000 (-0500)
Subject: Add the forward_euler1 function and a test for it.
X-Git-Url: https://gitweb.michael.orlitzky.com/?a=commitdiff_plain;h=24b6a4fe081d46f6a2f7ee2a3161401256d21fb5;p=octave.git

Add the forward_euler1 function and a test for it.
---

diff --git a/forward_euler1.m b/forward_euler1.m
new file mode 100644
index 0000000..3e1061d
--- /dev/null
+++ b/forward_euler1.m
@@ -0,0 +1,20 @@
+function y = forward_euler1(x0, y0, f, h)
+  ## Compute one iteration of the forward Euler method.
+  ##
+  ## INPUT:
+  ##
+  ##   * ``x0`` - The initial x-coordinate.
+  ##
+  ##   * ``y0`` - The initial value y(x0).
+  ##
+  ##   * ``f`` - The function y' = f(x,y) of two variables.
+  ##
+  ##   * ``h`` - The step size.
+  ##
+  ## OUTPUT:
+  ##
+  ## The approximate value of y(x) at x = x0+h.
+  ##
+  y_prime = f(x0,y0);
+  y = y0 +  h * y_prime;
+end
diff --git a/run-tests.m b/run-tests.m
index 2892ba0..2ff59a3 100755
--- a/run-tests.m
+++ b/run-tests.m
@@ -102,3 +102,16 @@ expected_root = [1.33635; 1.75424];
 unit_test_equals("Homework #3 problem #4 root is correct", ...
 		 expected_root, ...
 		 actual_root);
+
+
+
+f = @(x,y) y;
+x0 = 0;
+y0 = 1;
+h = 1;
+actual_y = forward_euler1(x0, y0, f, h);
+expected_y = 2;
+
+unit_test_equals("Forward Euler works for one step", ...
+		 expected_y, ...
+		 actual_y);