Occured -> Occurred.

Thanks to Phillip Huebner for reporting this.

Change-Id: I9cddfbb373aeb496961d08e434fe661bff4abd29
diff --git a/internal/ceres/evaluator_test.cc b/internal/ceres/evaluator_test.cc
index 7c234f3..48dc78a 100644
--- a/internal/ceres/evaluator_test.cc
+++ b/internal/ceres/evaluator_test.cc
@@ -252,7 +252,7 @@
   // the jacobian evaluation, but requires explicit handling in the evaluators.
   // At one point the compressed row evaluator had a bug that went undetected
   // for a long time, since by chance most users added parameters to the problem
-  // in the same order that they occured as parameters to a cost function.
+  // in the same order that they occurred as parameters to a cost function.
   problem.AddResidualBlock(new ParameterIgnoringCostFunction<1, 3, 4, 3, 2>,
                            NULL,
                            z, y, x);