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--- gibson:teaching:fall-2012:math445:hw1-solns [2012/10/05 07:20]
gibson created
+++ gibson:teaching:fall-2012:math445:hw1-solns [2012/10/08 12:36] (current)
gibson
@@ Line 145: / Line 145: @@
 <code>
-% argh, my code for this on my laptop at home; will fill in later
+function xcenter = bisectsearch(f, xleft, xright)
+% function xcenter = bisectsearch(f, xleft, xright)
+% find a zero of f between xleft and xright using bisection search algorithm
+  eps = 1e-13; % stopping condition: abs(f(xcenter)) < eps
+  fleft = f(xleft);
+  fright = f(xright);
+  % should put in check that fleft and fright have opposite signs
+  xcenter = 0.5*(xleft + xright);
+  fcenter = f(xcenter);
+  % repeat until f(xcenter) is close enough to zero
+  while (abs(fcenter) > eps)
+    if (sign(fleft) == sign(fcenter))
+      % replace the left stuff with the center stuff;
+      fleft = fcenter;
+      xleft = xcenter;
+    else
+      % replace the right stuff with the center stuff;
+      fright = fcenter;
+      xright = xcenter;
+    end
+    xcenter = 0.5*(xleft + xright);
+    fcenter = f(xcenter);
+  end
+end
 </code>

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