diff --git a/examples/bundle_adjuster.cc b/examples/bundle_adjuster.cc
index f5c1ac1..e5f9100 100644
--- a/examples/bundle_adjuster.cc
+++ b/examples/bundle_adjuster.cc
@@ -66,27 +66,30 @@
 #include "snavely_reprojection_error.h"
 
 DEFINE_string(input, "", "Input File name");
+DEFINE_string(trust_region_strategy, "levenberg_marquardt",
+              "Options are: levenberg_marquardt, dogleg");
+DEFINE_string(linear_solver, "sparse_schur", "Options are: "
+              "sparse_schur, dense_schur, iterative_schur, sparse_normal_cholesky, "
+              "dense_qr, dense_normal_cholesky and cgnr");
+DEFINE_string(preconditioner, "jacobi", "Options are: "
+              "identity, jacobi, schur_jacobi, cluster_jacobi, "
+              "cluster_tridiagonal");
+DEFINE_string(sparse_linear_algebra_library, "suite_sparse",
+              "Options are: suite_sparse and cx_sparse");
+DEFINE_string(ordering, "schur", "Options are: schur, user, natural");
+DEFINE_string(dogleg, "traditional_dogleg", "Options are: traditional_dogleg,"
+              "subspace_dogleg");
+
 DEFINE_bool(use_quaternions, false, "If true, uses quaternions to represent "
             "rotations. If false, angle axis is used");
 DEFINE_bool(use_local_parameterization, false, "For quaternions, use a local "
             "parameterization.");
 DEFINE_bool(robustify, false, "Use a robust loss function");
 
-DEFINE_string(trust_region_strategy, "lm", "Options are: lm, dogleg");
 DEFINE_double(eta, 1e-2, "Default value for eta. Eta determines the "
              "accuracy of each linear solve of the truncated newton step. "
              "Changing this parameter can affect solve performance ");
-DEFINE_string(solver_type, "sparse_schur", "Options are: "
-              "sparse_schur, dense_schur, iterative_schur, sparse_cholesky, "
-              "dense_qr, dense_cholesky and conjugate_gradients");
-DEFINE_string(preconditioner_type, "jacobi", "Options are: "
-              "identity, jacobi, schur_jacobi, cluster_jacobi, "
-              "cluster_tridiagonal");
-DEFINE_string(sparse_linear_algebra_library, "suitesparse",
-              "Options are: suitesparse and cxsparse");
 
-DEFINE_string(ordering_type, "schur", "Options are: schur, user, natural");
-DEFINE_string(dogleg_type, "traditional", "Options are: traditional, subspace");
 DEFINE_bool(use_block_amd, true, "Use a block oriented fill reducing "
             "ordering.");
 
@@ -111,88 +114,19 @@
 namespace examples {
 
 void SetLinearSolver(Solver::Options* options) {
-  if (FLAGS_solver_type == "sparse_schur") {
-    options->linear_solver_type = ceres::SPARSE_SCHUR;
-  } else if (FLAGS_solver_type == "dense_schur") {
-    options->linear_solver_type = ceres::DENSE_SCHUR;
-  } else if (FLAGS_solver_type == "iterative_schur") {
-    options->linear_solver_type = ceres::ITERATIVE_SCHUR;
-  } else if (FLAGS_solver_type == "sparse_cholesky") {
-    options->linear_solver_type = ceres::SPARSE_NORMAL_CHOLESKY;
-  } else if (FLAGS_solver_type == "cgnr") {
-    options->linear_solver_type = ceres::CGNR;
-  } else if (FLAGS_solver_type == "dense_qr") {
-    // DENSE_QR is included here for completeness, but actually using
-    // this option is a bad idea due to the amount of memory needed
-    // to store even the smallest of the bundle adjustment jacobian
-    // arrays
-    options->linear_solver_type = ceres::DENSE_QR;
-  } else if (FLAGS_solver_type == "dense_cholesky") {
-    // DENSE_NORMAL_CHOLESKY is included here for completeness, but
-    // actually using this option is a bad idea due to the amount of
-    // memory needed to store even the smallest of the bundle
-    // adjustment jacobian arrays
-    options->linear_solver_type = ceres::DENSE_NORMAL_CHOLESKY;
-  } else {
-    LOG(FATAL) << "Unknown ceres solver type: "
-               << FLAGS_solver_type;
-  }
-
-  if (options->linear_solver_type == ceres::CGNR) {
-    options->linear_solver_min_num_iterations = 5;
-    if (FLAGS_preconditioner_type == "identity") {
-      options->preconditioner_type = ceres::IDENTITY;
-    } else if (FLAGS_preconditioner_type == "jacobi") {
-      options->preconditioner_type = ceres::JACOBI;
-    } else {
-      LOG(FATAL) << "For CGNR, only identity and jacobian "
-                 << "preconditioners are supported. Got: "
-                 << FLAGS_preconditioner_type;
-    }
-  }
-
-  if (options->linear_solver_type == ceres::ITERATIVE_SCHUR) {
-    options->linear_solver_min_num_iterations = 5;
-    if (FLAGS_preconditioner_type == "identity") {
-      options->preconditioner_type = ceres::IDENTITY;
-    } else if (FLAGS_preconditioner_type == "jacobi") {
-      options->preconditioner_type = ceres::JACOBI;
-    } else if (FLAGS_preconditioner_type == "schur_jacobi") {
-      options->preconditioner_type = ceres::SCHUR_JACOBI;
-    } else if (FLAGS_preconditioner_type == "cluster_jacobi") {
-      options->preconditioner_type = ceres::CLUSTER_JACOBI;
-    } else if (FLAGS_preconditioner_type == "cluster_tridiagonal") {
-      options->preconditioner_type = ceres::CLUSTER_TRIDIAGONAL;
-    } else {
-      LOG(FATAL) << "Unknown ceres preconditioner type: "
-                 << FLAGS_preconditioner_type;
-    }
-  }
-
-  if (FLAGS_sparse_linear_algebra_library == "suitesparse") {
-    options->sparse_linear_algebra_library = SUITE_SPARSE;
-  } else if (FLAGS_sparse_linear_algebra_library == "cxsparse") {
-    options->sparse_linear_algebra_library = CX_SPARSE;
-  } else {
-    LOG(FATAL) << "Unknown sparse linear algebra library type.";
-  }
-
+  CHECK(StringToLinearSolverType(FLAGS_linear_solver,
+                                 &options->linear_solver_type));
+  CHECK(StringToPreconditionerType(FLAGS_preconditioner,
+                                   &options->preconditioner_type));
+  CHECK(StringToSparseLinearAlgebraLibraryType(
+            FLAGS_sparse_linear_algebra_library,
+            &options->sparse_linear_algebra_library));
   options->num_linear_solver_threads = FLAGS_num_threads;
 }
 
 void SetOrdering(BALProblem* bal_problem, Solver::Options* options) {
   options->use_block_amd = FLAGS_use_block_amd;
-
-  // Only non-Schur solvers support the natural ordering for this
-  // problem.
-  if (FLAGS_ordering_type == "natural") {
-    if (options->linear_solver_type == SPARSE_SCHUR ||
-        options->linear_solver_type == DENSE_SCHUR ||
-        options->linear_solver_type == ITERATIVE_SCHUR) {
-      LOG(FATAL) << "Natural ordering with Schur type solver does not work.";
-    }
-    return;
-  }
+  CHECK(StringToOrderingType(FLAGS_ordering, &options->ordering_type));
 
   // Bundle adjustment problems have a sparsity structure that makes
   // them amenable to more specialized and much more efficient
@@ -208,8 +142,7 @@
   // the right ParameterBlock ordering, or by manually specifying a
   // suitable ordering vector and defining
   // Options::num_eliminate_blocks.
-  if (FLAGS_ordering_type == "schur") {
-    options->ordering_type = ceres::SCHUR;
+  if (options->ordering_type == ceres::SCHUR) {
     return;
   }
 
@@ -248,22 +181,9 @@
   options->eta = FLAGS_eta;
   options->max_solver_time_in_seconds = FLAGS_max_solver_time;
   options->use_nonmonotonic_steps = FLAGS_nonmonotonic_steps;
-  if (FLAGS_trust_region_strategy == "lm") {
-    options->trust_region_strategy_type = LEVENBERG_MARQUARDT;
-  } else if (FLAGS_trust_region_strategy == "dogleg") {
-    options->trust_region_strategy_type = DOGLEG;
-  } else {
-    LOG(FATAL) << "Unknown trust region strategy: "
-               << FLAGS_trust_region_strategy;
-  }
-  if (FLAGS_dogleg_type == "traditional") {
-    options->dogleg_type = TRADITIONAL_DOGLEG;
-  } else if (FLAGS_dogleg_type == "subspace") {
-    options->dogleg_type = SUBSPACE_DOGLEG;
-  } else {
-    LOG(FATAL) << "Unknown dogleg type: "
-               << FLAGS_dogleg_type;
-  }
+  CHECK(StringToTrustRegionStrategyType(FLAGS_trust_region_strategy,
+                                        &options->trust_region_strategy_type));
+  CHECK(StringToDoglegType(FLAGS_dogleg, &options->dogleg_type));
 }
 
 void SetSolverOptionsFromFlags(BALProblem* bal_problem,
diff --git a/examples/nist.cc b/examples/nist.cc
index 2c1a4c5..0f5951f 100644
--- a/examples/nist.cc
+++ b/examples/nist.cc
@@ -51,6 +51,18 @@
 
 DEFINE_string(nist_data_dir, "", "Directory containing the NIST non-linear"
               "regression examples");
+DEFINE_string(trust_region_strategy, "levenberg_marquardt",
+              "Options are: levenberg_marquardt, dogleg");
+DEFINE_string(dogleg, "traditional_dogleg",
+              "Options are: traditional_dogleg, subspace_dogleg");
+DEFINE_string(linear_solver, "dense_qr", "Options are: "
+              "sparse_cholesky, dense_qr, dense_normal_cholesky and"
+              "cgnr");
+DEFINE_string(preconditioner, "jacobi", "Options are: "
+              "identity, jacobi");
+DEFINE_int32(num_iterations, 10000, "Number of iterations");
+DEFINE_bool(nonmonotonic_steps, false, "Trust region algorithm can use"
+            " nonmonotic steps");
 
 using Eigen::Dynamic;
 using Eigen::RowMajor;
@@ -120,8 +132,13 @@
      final_parameters_(0, parameter_id) = std::atof(pieces[2 + kNumTries].c_str());
     }
 
+    // Certfied cost
+    SkipLines(ifs, 1);
+    GetAndSplitLine(ifs, &pieces);
+    certified_cost_ = std::atof(pieces[4].c_str()) / 2.0;
+
     // Read the observations.
-    SkipLines(ifs, 20 - kNumParameters);
+    SkipLines(ifs, 18 - kNumParameters);
     for (int i = 0; i < kNumObservations; ++i) {
       GetAndSplitLine(ifs, &pieces);
       // Response.
@@ -145,12 +162,14 @@
   int response_size()       const { return response_.cols();   }
   int num_parameters()      const { return initial_parameters_.cols(); }
   int num_starts()          const { return initial_parameters_.rows(); }
+  double certified_cost()   const { return certified_cost_; }
 
  private:
   Matrix predictor_;
   Matrix response_;
   Matrix initial_parameters_;
   Matrix final_parameters_;
+  double certified_cost_;
 };
 
 #define NIST_BEGIN(CostFunctionName) \
@@ -340,27 +359,7 @@
     Solve(options, &problem, &summaries[start]);
   }
 
-  // Ugly hack to get the objective function value at the certified
-  // optimal parameter values. So we build the problem and call Ceres
-  // with zero iterations to get the initial_cost.
-  {
-    Matrix initial_parameters = nist_problem.final_parameters();
-    ceres::Problem problem;
-    for (int i = 0; i < nist_problem.num_observations(); ++i) {
-      problem.AddResidualBlock(
-          new ceres::AutoDiffCostFunction<Model, num_residuals, num_parameters>(
-              new Model(predictor.data() + nist_problem.predictor_size() * i,
-                        response.data() + nist_problem.response_size() * i)),
-          NULL,
-          initial_parameters.data());
-    }
-
-    ceres::Solver::Options options;
-    options.max_num_iterations = 0;
-    Solve(options, &problem, &summaries[nist_problem.num_starts()]);
-  }
-
-  double certified_cost = summaries[nist_problem.num_starts()].initial_cost;
+  const double certified_cost = nist_problem.certified_cost();
 
   int num_success = 0;
   const int kMinNumMatchingDigits = 4;
@@ -380,6 +379,7 @@
       std::cerr <<  "FAILURE";
       std::cerr << " summary: "
                 << summary.BriefReport()
+                << " Certified cost: " << certified_cost
                 << std::endl;
     } else {
       ++num_success;
@@ -389,7 +389,31 @@
   return num_success;
 }
 
-void SolveNISTProblems(const ceres::Solver::Options& options) {
+void SetMinimizerOptions(ceres::Solver::Options* options) {
+  CHECK(ceres::StringToLinearSolverType(FLAGS_linear_solver,
+                                        &options->linear_solver_type));
+  CHECK(ceres::StringToPreconditionerType(FLAGS_preconditioner,
+                                          &options->preconditioner_type));
+  CHECK(ceres::StringToTrustRegionStrategyType(
+            FLAGS_trust_region_strategy,
+            &options->trust_region_strategy_type));
+  CHECK(ceres::StringToDoglegType(FLAGS_dogleg, &options->dogleg_type));
+
+  options->max_num_iterations = FLAGS_num_iterations;
+  options->use_nonmonotonic_steps = FLAGS_nonmonotonic_steps;
+  options->function_tolerance = 1e-18;
+  options->gradient_tolerance = 1e-18;
+  options->parameter_tolerance = 1e-18;
+}
+
+void SolveNISTProblems() {
+  if (FLAGS_nist_data_dir.empty()) {
+    LOG(FATAL) << "Must specify the directory containing the NIST problems";
+  }
+
+  ceres::Solver::Options options;
+  SetMinimizerOptions(&options);
+
   std::cerr << "Lower Difficulty\n";
   int easy_success = 0;
   easy_success += RegressionDriver<Misra1a,  1, 2>("Misra1a.dat",  options);
@@ -437,50 +461,6 @@
 int main(int argc, char** argv) {
   google::ParseCommandLineFlags(&argc, &argv, true);
   google::InitGoogleLogging(argv[0]);
-
-  // TODO(sameeragarwal): Test more combinations of non-linear and
-  // linear solvers.
-  ceres::Solver::Options options;
-  options.max_num_iterations = 10000;
-  options.function_tolerance *= 1e-10;
-  options.gradient_tolerance *= 1e-10;
-  options.parameter_tolerance *= 1e-10;
-
-  options.linear_solver_type = ceres::DENSE_QR;
-  options.trust_region_strategy_type = ceres::LEVENBERG_MARQUARDT;
-  std::cerr << "Levenberg-Marquardt - DENSE_QR\n";
-  SolveNISTProblems(options);
-
-  options.trust_region_strategy_type = ceres::DOGLEG;
-  options.dogleg_type = ceres::TRADITIONAL_DOGLEG;
-  std::cerr << "\n\nTraditional Dogleg - DENSE_QR\n\n";
-  SolveNISTProblems(options);
-
-  options.trust_region_strategy_type = ceres::DOGLEG;
-  options.dogleg_type = ceres::SUBSPACE_DOGLEG;
-  std::cerr << "\n\nSubspace Dogleg - DENSE_QR\n\n";
-  SolveNISTProblems(options);
-
-  options.linear_solver_type = ceres::DENSE_NORMAL_CHOLESKY;
-  options.trust_region_strategy_type = ceres::LEVENBERG_MARQUARDT;
-  std::cerr << "Levenberg-Marquardt - DENSE_NORMAL_CHOLESKY\n";
-  SolveNISTProblems(options);
-
-  options.trust_region_strategy_type = ceres::DOGLEG;
-  options.dogleg_type = ceres::TRADITIONAL_DOGLEG;
-  std::cerr << "\n\nTraditional Dogleg - DENSE_NORMAL_CHOLESKY\n\n";
-  SolveNISTProblems(options);
-
-  options.trust_region_strategy_type = ceres::DOGLEG;
-  options.dogleg_type = ceres::SUBSPACE_DOGLEG;
-  std::cerr << "\n\nSubspace Dogleg - DENSE_NORMAL_CHOLESKY\n\n";
-  SolveNISTProblems(options);
-
-  options.linear_solver_type = ceres::CGNR;
-  options.preconditioner_type = ceres::JACOBI;
-  options.trust_region_strategy_type = ceres::LEVENBERG_MARQUARDT;
-  std::cerr << "Levenberg-Marquardt - CGNR + JACOBI\n";
-  SolveNISTProblems(options);
-
+  SolveNISTProblems();
   return 0;
 };
diff --git a/include/ceres/types.h b/include/ceres/types.h
index 3980885..2c0b7bd 100644
--- a/include/ceres/types.h
+++ b/include/ceres/types.h
@@ -37,6 +37,8 @@
 #ifndef CERES_PUBLIC_TYPES_H_
 #define CERES_PUBLIC_TYPES_H_
 
+#include "ceres/internal/port.h"
+
 namespace ceres {
 
 // Basic integer types. These typedefs are in the Ceres namespace to avoid
@@ -297,16 +299,31 @@
 };
 
 const char* LinearSolverTypeToString(LinearSolverType type);
+bool StringToLinearSolverType(string value, LinearSolverType* type);
+
 const char* PreconditionerTypeToString(PreconditionerType type);
+bool StringToPreconditionerType(string value, PreconditionerType* type);
+
 const char* SparseLinearAlgebraLibraryTypeToString(
     SparseLinearAlgebraLibraryType type);
+bool StringToSparseLinearAlgebraLibraryType(
+    string value,
+    SparseLinearAlgebraLibraryType* type);
+
+const char* OrderingTypeToString(OrderingType type);
+bool StringToOrderingType(string value, OrderingType* type);
+
+const char* TrustRegionStrategyTypeToString(TrustRegionStrategyType type);
+bool StringToTrustRegionStrategyType(string value,
+                                     TrustRegionStrategyType* type);
+
+const char* DoglegTypeToString(DoglegType type);
+bool StringToDoglegType(string value, DoglegType* type);
+
 const char* LinearSolverTerminationTypeToString(
     LinearSolverTerminationType type);
-const char* OrderingTypeToString(OrderingType type);
+
 const char* SolverTerminationTypeToString(SolverTerminationType type);
-const char* SparseLinearAlgebraLibraryTypeToString(
-    SparseLinearAlgebraLibraryType type);
-const char* TrustRegionStrategyTypeToString( TrustRegionStrategyType type);
 bool IsSchurType(LinearSolverType type);
 
 }  // namespace ceres
diff --git a/internal/ceres/types.cc b/internal/ceres/types.cc
index 2e950c5..9339bc4 100644
--- a/internal/ceres/types.cc
+++ b/internal/ceres/types.cc
@@ -28,13 +28,21 @@
 //
 // Author: sameeragarwal@google.com (Sameer Agarwal)
 
+#include <algorithm>
 #include <string>
 #include "ceres/types.h"
+#include "glog/logging.h"
 
 namespace ceres {
 
 #define CASESTR(x) case x: return #x
 
+#define STRENUM(x) if (value == #x) { *type = x; return true;}
+
+void UpperCase(string* input) {
+  std::transform(input->begin(), input->end(), input->begin(), ::toupper);
+}
+
 const char* LinearSolverTypeToString(LinearSolverType solver_type) {
   switch (solver_type) {
     CASESTR(DENSE_NORMAL_CHOLESKY);
@@ -49,6 +57,18 @@
   }
 }
 
+bool StringToLinearSolverType(string value, LinearSolverType* type) {
+  UpperCase(&value);
+  STRENUM(DENSE_NORMAL_CHOLESKY);
+  STRENUM(DENSE_QR);
+  STRENUM(SPARSE_NORMAL_CHOLESKY);
+  STRENUM(DENSE_SCHUR);
+  STRENUM(SPARSE_SCHUR);
+  STRENUM(ITERATIVE_SCHUR);
+  STRENUM(CGNR);
+  return false;
+}
+
 const char* PreconditionerTypeToString(
     PreconditionerType preconditioner_type) {
   switch (preconditioner_type) {
@@ -62,6 +82,16 @@
   }
 }
 
+bool StringToPreconditionerType(string value, PreconditionerType* type) {
+  UpperCase(&value);
+  STRENUM(IDENTITY);
+  STRENUM(JACOBI);
+  STRENUM(SCHUR_JACOBI);
+  STRENUM(CLUSTER_JACOBI);
+  STRENUM(CLUSTER_TRIDIAGONAL);
+  return false;
+}
+
 const char* SparseLinearAlgebraLibraryTypeToString(
     SparseLinearAlgebraLibraryType sparse_linear_algebra_library_type) {
   switch (sparse_linear_algebra_library_type) {
@@ -72,6 +102,16 @@
   }
 }
 
+
+bool StringToSparseLinearAlgebraLibraryType(
+    string value,
+    SparseLinearAlgebraLibraryType* type) {
+  UpperCase(&value);
+  STRENUM(SUITE_SPARSE);
+  STRENUM(CX_SPARSE);
+  return false;
+}
+
 const char* OrderingTypeToString(OrderingType ordering_type) {
   switch (ordering_type) {
     CASESTR(NATURAL);
@@ -82,6 +122,48 @@
   }
 }
 
+bool StringToOrderingType(string value, OrderingType* type) {
+  UpperCase(&value);
+  STRENUM(NATURAL);
+  STRENUM(USER);
+  STRENUM(SCHUR);
+  return false;
+}
+
+const char* TrustRegionStrategyTypeToString(
+    TrustRegionStrategyType trust_region_strategy_type) {
+  switch (trust_region_strategy_type) {
+    CASESTR(LEVENBERG_MARQUARDT);
+    CASESTR(DOGLEG);
+    default:
+      return "UNKNOWN";
+  }
+}
+
+bool StringToTrustRegionStrategyType(string value,
+                                     TrustRegionStrategyType* type) {
+  UpperCase(&value);
+  STRENUM(LEVENBERG_MARQUARDT);
+  STRENUM(DOGLEG);
+  return false;
+}
+
+const char* DoglegTypeToString(DoglegType dogleg_type) {
+  switch (dogleg_type) {
+    CASESTR(TRADITIONAL_DOGLEG);
+    CASESTR(SUBSPACE_DOGLEG);
+    default:
+      return "UNKNOWN";
+  }
+}
+
+bool StringToDoglegType(string value, DoglegType* type) {
+  UpperCase(&value);
+  STRENUM(TRADITIONAL_DOGLEG);
+  STRENUM(SUBSPACE_DOGLEG);
+  return false;
+}
+
 const char* SolverTerminationTypeToString(
     SolverTerminationType termination_type) {
   switch (termination_type) {
@@ -98,27 +180,20 @@
   }
 }
 
-const char* SparseLinearAlgebraTypeToString(
-    SparseLinearAlgebraLibraryType sparse_linear_algebra_library_type) {
-  switch (sparse_linear_algebra_library_type) {
-    CASESTR(CX_SPARSE);
-    CASESTR(SUITE_SPARSE);
-    default:
-      return "UNKNOWN";
-  }
-}
-
-const char* TrustRegionStrategyTypeToString(
-    TrustRegionStrategyType trust_region_strategy_type) {
-  switch (trust_region_strategy_type) {
-    CASESTR(LEVENBERG_MARQUARDT);
-    CASESTR(DOGLEG);
+const char* LinearSolverTerminationTypeToString(
+    LinearSolverTerminationType termination_type) {
+  switch (termination_type) {
+    CASESTR(TOLERANCE);
+    CASESTR(MAX_ITERATIONS);
+    CASESTR(STAGNATION);
+    CASESTR(FAILURE);
     default:
       return "UNKNOWN";
   }
 }
 
 #undef CASESTR
+#undef STRENUM
 
 bool IsSchurType(LinearSolverType type) {
   return ((type == SPARSE_SCHUR) ||