Minor fixes Based on William Rucklidge's review, including a nasty bug in parameter block removal. Change-Id: I3a692e589f600ff560ecae9fa85bb0b76063d403

diff --git a/internal/ceres/block_jacobi_preconditioner.h b/internal/ceres/block_jacobi_preconditioner.h
index 32221f5..ed5eebc 100644
--- a/internal/ceres/block_jacobi_preconditioner.h
+++ b/internal/ceres/block_jacobi_preconditioner.h

@@ -54,7 +54,7 @@
 class BlockJacobiPreconditioner : public Preconditioner {
  public:
   // A must remain valid while the BlockJacobiPreconditioner is.
-  BlockJacobiPreconditioner(const BlockSparseMatrixBase& A);
+  explicit BlockJacobiPreconditioner(const BlockSparseMatrixBase& A);
   virtual ~BlockJacobiPreconditioner();
 
   // Preconditioner interface

diff --git a/internal/ceres/iterative_schur_complement_solver.cc b/internal/ceres/iterative_schur_complement_solver.cc
index c44bd39..d352d02 100644
--- a/internal/ceres/iterative_schur_complement_solver.cc
+++ b/internal/ceres/iterative_schur_complement_solver.cc

@@ -110,12 +110,6 @@
     case IDENTITY:
       break;
     case JACOBI:
-      // We need to strip the constness of the block_diagonal_FtF_inverse
-      // matrix here because the only other way to initialize the struct
-      // cg_solve_options would be to add a constructor to it. We know
-      // that the only method ever called on the preconditioner is the
-      // RightMultiply which is a const method so we don't need to worry
-      // about the object getting modified.
       preconditioner_.reset(
           new SparseMatrixPreconditionerWrapper(
               schur_complement_->block_diagonal_FtF_inverse()));

diff --git a/internal/ceres/parameter_block.h b/internal/ceres/parameter_block.h
index 3a709f4..b1e8d93 100644
--- a/internal/ceres/parameter_block.h
+++ b/internal/ceres/parameter_block.h

@@ -73,7 +73,7 @@
 
   // Create a parameter block with the user state, size, and index specified.
   // The size is the size of the parameter block and the index is the position
-  // if the parameter block inside a Program (if any).
+  // of the parameter block inside a Program (if any).
   ParameterBlock(double* user_state, int size, int index) {
     Init(user_state, size, index, NULL);
   }

diff --git a/internal/ceres/preconditioner.h b/internal/ceres/preconditioner.h
index 77280c3..5bb077e 100644
--- a/internal/ceres/preconditioner.h
+++ b/internal/ceres/preconditioner.h

@@ -69,11 +69,11 @@
     //
     // For example if elimination_groups is a vector of size k, then
     // the linear solver is informed that it should eliminate the
-    // parameter blocks 0 - elimination_groups[0] - 1 first, and then
-    // elimination_groups[0] - elimination_groups[1] and so on. Within
-    // each elimination group, the linear solver is free to choose how
-    // the parameter blocks are ordered. Different linear solvers have
-    // differing requirements on elimination_groups.
+    // parameter blocks 0 ... elimination_groups[0] - 1 first, and
+    // then elimination_groups[0] ... elimination_groups[1] and so
+    // on. Within each elimination group, the linear solver is free to
+    // choose how the parameter blocks are ordered. Different linear
+    // solvers have differing requirements on elimination_groups.
     //
     // The most common use is for Schur type solvers, where there
     // should be at least two elimination groups and the first
@@ -130,7 +130,7 @@
 class SparseMatrixPreconditionerWrapper : public Preconditioner {
  public:
   // Wrapper does NOT take ownership of the matrix pointer.
-  SparseMatrixPreconditionerWrapper(const SparseMatrix* matrix);
+  explicit SparseMatrixPreconditionerWrapper(const SparseMatrix* matrix);
   virtual ~SparseMatrixPreconditionerWrapper();
 
   // Preconditioner interface

diff --git a/internal/ceres/problem_impl.cc b/internal/ceres/problem_impl.cc
index 6154ddf..ae4e7ed 100644
--- a/internal/ceres/problem_impl.cc
+++ b/internal/ceres/problem_impl.cc

@@ -177,7 +177,7 @@
 
 ProblemImpl::~ProblemImpl() {
   // Collect the unique cost/loss functions and delete the residuals.
-  const int num_residual_blocks =  program_->residual_blocks_.size();
+  const int num_residual_blocks = program_->residual_blocks_.size();
   cost_functions_to_delete_.reserve(num_residual_blocks);
   loss_functions_to_delete_.reserve(num_residual_blocks);
   for (int i = 0; i < program_->residual_blocks_.size(); ++i) {
@@ -486,8 +486,8 @@
       ResidualBlock* residual_block =
           (*(program_->mutable_residual_blocks()))[i];
       const int num_parameter_blocks = residual_block->NumParameterBlocks();
-      for (int i = 0; i < num_parameter_blocks; ++i) {
-        if (residual_block->parameter_blocks()[i] == parameter_block) {
+      for (int j = 0; j < num_parameter_blocks; ++j) {
+        if (residual_block->parameter_blocks()[j] == parameter_block) {
           RemoveResidualBlock(residual_block);
           // The parameter blocks are guaranteed unique.
           break;

diff --git a/internal/ceres/solver.cc b/internal/ceres/solver.cc
index 6d38535..b1bd2d8 100644
--- a/internal/ceres/solver.cc
+++ b/internal/ceres/solver.cc

@@ -311,7 +311,7 @@
 
     StringAppendF(&report, "\n");
 
-    StringAppendF(&report,   "%45s    %21s\n", "Given",  "Used");
+    StringAppendF(&report, "%45s    %21s\n", "Given",  "Used");
     StringAppendF(&report, "Threads:            % 25d% 25d\n",
                   num_threads_given, num_threads_used);
 

diff --git a/internal/ceres/stl_util.h b/internal/ceres/stl_util.h
index 5e92eff..b23e7c1 100644
--- a/internal/ceres/stl_util.h
+++ b/internal/ceres/stl_util.h

@@ -53,6 +53,8 @@
   }
 }
 
+// Variant of STLDeleteContainerPointers which allows the container to
+// contain duplicates.
 template <class ForwardIterator>
 void STLDeleteUniqueContainerPointers(ForwardIterator begin,
                                       ForwardIterator end) {