Fixes for some line search bugs & corner cases.
- Increase precision of numeric values output in error messages to
allow for easier debugging.
- Ensure termination after Wolfe search bracketing phase if bracket
width has been shrunk to below tolerance.
- Cleaned up return value for BracketingPhase(), now false iff
optimisation should stop, true otherwise.
- Fix bug whereby we would mark a step size as satisfying the Wolfe
conditions when it did not due to numerical issues in the cost
function.
- Adding explanation of a subtlety in which a zoom could still be
acceptably invoked with bracket_low.f > bracket_high.f.
- Replacing hard check of a pre-condition of ZoomPhase() with a
conditional return if not satisfied to address issue whereby a
bracket could be incorrectly identified due to inconsistent values
& gradients returned from the cost function.
- Adding missing check for step size validity in line search minimizer.
- Adding ToDebugString() for FunctionSample.
Change-Id: Iad98e635749877f80c079ebad126bf022d82232d
diff --git a/internal/ceres/polynomial.cc b/internal/ceres/polynomial.cc
index 3238b89..feec884 100644
--- a/internal/ceres/polynomial.cc
+++ b/internal/ceres/polynomial.cc
@@ -37,6 +37,7 @@
#include "Eigen/Dense"
#include "ceres/internal/port.h"
+#include "ceres/stringprintf.h"
#include "glog/logging.h"
namespace ceres {
@@ -255,6 +256,12 @@
}
}
+string FunctionSample::ToDebugString() const {
+ return StringPrintf("[x: %.8e, value: %.8e, gradient: %.8e, "
+ "value_is_valid: %d, gradient_is_valid: %d]",
+ x, value, gradient, value_is_valid, gradient_is_valid);
+}
+
Vector FindInterpolatingPolynomial(const vector<FunctionSample>& samples) {
const int num_samples = samples.size();
int num_constraints = 0;
