Fix typos.

Contributed by Ishamis@, IanBoyanZhang@, gkrobner@ & mithunjacob@.

Change-Id: Iab3c19a07a6f3db2486e3557dcb55bfe5de2aee5

include/ceres/local_parameterization.h

@@ -90,8 +90,8 @@ namespace ceres {
 //
 // An example that occurs commonly in Structure from Motion problems
 // is when camera rotations are parameterized using Quaternion. There,
-// it is useful only make updates orthogonal to that 4-vector defining
-// the quaternion. One way to do this is to let delta be a 3
+// it is useful to only make updates orthogonal to that 4-vector
+// defining the quaternion. One way to do this is to let delta be a 3
 // dimensional vector and define Plus to be
 //
 //   Plus(x, delta) = [cos(|delta|), sin(|delta|) delta / |delta|] * x
@@ -99,7 +99,7 @@ namespace ceres {
 // The multiplication between the two 4-vectors on the RHS is the
 // standard quaternion product.
 //
-// Given g and a point x, optimizing f can now be restated as
+// Given f and a point x, optimizing f can now be restated as
 //
 //     min  f(Plus(x, delta))
 //    delta