Fix 3+ nested Jet constructor
In Jet types, there is an attempt to set the derivative to 0.
However, if the derivative is not directly a scalar but a Jet<Jet>,
this cannot be constructed directly from a 0 literal. This is solved
by using the default constructor for the scalar type instead of 0.
The typical use case for this is adding constraints to the second
derivative of a curve in an Autodiff cost function.
Change-Id: Id480096632a731f312be12e294b3d6e244211529
diff --git a/include/ceres/jet.h b/include/ceres/jet.h
index 1879ea1..1f81743 100644
--- a/include/ceres/jet.h
+++ b/include/ceres/jet.h
@@ -179,18 +179,18 @@
// (where T is a Jet<T, N>). This usually only happens in opt mode. Note that
// the C++ standard mandates that e.g. default constructed doubles are
// initialized to 0.0; see sections 8.5 of the C++03 standard.
- Jet() : a() { v.setZero(); }
+ Jet() : a() { v.setConstant(Scalar()); }
// Constructor from scalar: a + 0.
explicit Jet(const T& value) {
a = value;
- v.setZero();
+ v.setConstant(Scalar());
}
// Constructor from scalar plus variable: a + t_i.
Jet(const T& value, int k) {
a = value;
- v.setZero();
+ v.setConstant(Scalar());
v[k] = T(1.0);
}
diff --git a/internal/ceres/jet_test.cc b/internal/ceres/jet_test.cc
index dff660b..a6cad62 100644
--- a/internal/ceres/jet_test.cc
+++ b/internal/ceres/jet_test.cc
@@ -899,5 +899,28 @@
ExpectJetsClose(r4(1), r4(1));
}
+TEST(Jet, nested3x) {
+ typedef Jet<J,2> JJ;
+ typedef Jet<JJ,2> JJJ;
+
+ JJJ x;
+ x.a = JJ(J(1, 0), 0);
+ x.v[0] = JJ(J(1));
+
+ JJJ y = x * x * x;
+
+ ExpectClose(y.a.a.a, 1, kTolerance);
+ ExpectClose(y.v[0].a.a, 3., kTolerance);
+ ExpectClose(y.v[0].v[0].a, 6., kTolerance);
+ ExpectClose(y.v[0].v[0].v[0], 6., kTolerance);
+
+ JJJ e = exp(x);
+
+ ExpectClose(e.a.a.a, kE, kTolerance);
+ ExpectClose(e.v[0].a.a, kE, kTolerance);
+ ExpectClose(e.v[0].v[0].a, kE, kTolerance);
+ ExpectClose(e.v[0].v[0].v[0], kE, kTolerance);
+}
+
} // namespace internal
} // namespace ceres
