Hi Rasmus,
You are right. This abbreviated declaration of Jet
template <typename T, int N>
struct Jet {
enum { DIMENSION = N };
using Scalar = T;
// Default-construct "a" because otherwise this can lead to false errors
about
// uninitialized uses when other classes relying on default constructed T
// (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.setConstant(Scalar()); }
// Constructor from scalar: a + 0.
explicit Jet(const T& value) {
a = value;
v.setConstant(Scalar());
}
// The scalar part.
T a;
// The infinitesimal part.
Eigen::Matrix<T, N, 1> v;
};
It has default zero initialized CTOR and CTOR initializing Jet from
floating value. Of course instead of using Mat::Zero() -> return
Mat::Constant(0) I can use Mat::Constant(0.0).
ср, 22 июн. 2022 г. в 19:00, Rasmus Munk Larsen <[email protected]>:
> BTW: What happens if you do Mat x = Mat::Zero(10.0); ? Perhaps conversion
> from double or float work, because those types are "differentiable", as
> opposed to int.
>
> On Wed, Jun 22, 2022 at 5:13 AM Oleg Shirokobrod <
> [email protected]> wrote:
>
>> Hi,
>>
>> In the file CwiseNullaryOp.h the functions DenseBase<Derived>::Zero call
>> function DenseBase<Derived>::Constant which uses Scalar(0) for
>> zero-initialization. It gives compilation error for this line
>> using Mat = Eigen::Matrix<std::complex<ceres::Jet<double, 3>>, -1, 1, 0,
>> -1, 1>;
>> Mat x = Mat::Zero(10);
>> Here ceres::Jet<double, 3> is autodif type in ceres-solver. The problem
>> is that it is not always possible to make conversion from int. From the
>> other side for non-class-type scalar values, Scalar() provides a temporary
>> which is zero-initialized. It is likely that for custom numerical class
>> types Scalar() provides zero-initialized temporary. This is the case for
>> Jet. When I replaced
>>
>> return Constant(size, Scalar(0));
>>
>> with
>>
>> return Constant(size, Scalar());
>>
>> in all Zero and setZero functions, code was compiled without errors.
>>
>> Best,
>>
>> Oleg
>>
>>
