Rename a confusingly named member of Solver::Options

Solver::Options::numeric_derivative_relative_step_size to
Solver::Options::gradient_check_numeric_derivative_relative_step_size

Change-Id: Ib89ae3f87e588d4aba2a75361770d2cec26f07aa

docs/source/nnls_solving.rst

diff --git a/docs/source/nnls_solving.rst b/docs/source/nnls_solving.rst
index ccf43a5..110d6bd 100644
--- a/docs/source/nnls_solving.rst
+++ b/docs/source/nnls_solving.rst
@@ -1570,7 +1570,7 @@
    difference between an element in a Jacobian exceeds this number,
    then the Jacobian for that cost term is dumped.
 
-.. member:: double Solver::Options::numeric_derivative_relative_step_size
+.. member:: double Solver::Options::gradient_check_numeric_derivative_relative_step_size
 
    Default: ``1e-6``
 
@@ -1592,7 +1592,7 @@
 
    .. math::
 
-     \delta &= numeric\_derivative\_relative\_step\_size\\
+     \delta &= gradient\_check\_numeric\_derivative\_relative\_step\_size\\
      \Delta f &= \frac{f((1 + \delta)  x) - f(x)}{\delta x}
 
    The finite differencing is done along each dimension. The reason to

include/ceres/solver.h

diff --git a/include/ceres/solver.h b/include/ceres/solver.h
index 76f3ca7..0d77d24 100644
--- a/include/ceres/solver.h
+++ b/include/ceres/solver.h
@@ -134,7 +134,7 @@
       trust_region_problem_dump_format_type = TEXTFILE;
       check_gradients = false;
       gradient_check_relative_precision = 1e-8;
-      numeric_derivative_relative_step_size = 1e-6;
+      gradient_check_numeric_derivative_relative_step_size = 1e-6;
       update_state_every_iteration = false;
     }
 
@@ -716,7 +716,7 @@
     // slightly shifted values; for the case of central difference,
     // this is what gets evaluated:
     //
-    //   delta = numeric_derivative_relative_step_size;
+    //   delta = gradient_check_numeric_derivative_relative_step_size;
     //   f_initial  = f(x)
     //   f_forward  = f((1 + delta) * x)
     //   f_backward = f((1 - delta) * x)
@@ -733,7 +733,7 @@
     // theory a good choice is sqrt(eps) * x, which for doubles means
     // about 1e-8 * x. However, I have found this number too
     // optimistic. This number should be exposed for users to change.
-    double numeric_derivative_relative_step_size;
+    double gradient_check_numeric_derivative_relative_step_size;
 
     // If true, the user's parameter blocks are updated at the end of
     // every Minimizer iteration, otherwise they are updated when the

internal/ceres/solver.cc

diff --git a/internal/ceres/solver.cc b/internal/ceres/solver.cc
index 5cc0a66..8411350 100644
--- a/internal/ceres/solver.cc
+++ b/internal/ceres/solver.cc
@@ -94,7 +94,7 @@
   OPTION_GT(num_linear_solver_threads, 0);
   if (options.check_gradients) {
     OPTION_GT(gradient_check_relative_precision, 0.0);
-    OPTION_GT(numeric_derivative_relative_step_size, 0.0);
+    OPTION_GT(gradient_check_numeric_derivative_relative_step_size, 0.0);
   }
   return true;
 }
@@ -507,7 +507,7 @@
     gradient_checking_problem.reset(
         CreateGradientCheckingProblemImpl(
             problem_impl,
-            options.numeric_derivative_relative_step_size,
+            options.gradient_check_numeric_derivative_relative_step_size,
             options.gradient_check_relative_precision,
             &gradient_checking_callback));
     problem_impl = gradient_checking_problem.get();