cast from T(Jet) to double

[坂井敦]

Hi.

I use ceres solver for robotics and I love it!

I have a question.
I want to use the pow function of math.h in the bool operator[] function like this.

template <typename T>
   bool operator()(const T* const x, T* residual) const {
     residual[0] = pow(x,1.5) ;
     return true;
   }

However, x's type is T(Jet), so I cannot compile it.
What is the easiest way to cast from T(Jet) to double?

Thanks in advance.

Atsushi 

[Sameer Agarwal]

you should not and cannot cast from jet to double. that will lead to you destroying the differentiation logic.

ceres comes with pow function that you should be able to use. there is an overload defined in jet.h.

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[坂井敦]

Hi Sameer.

Thank you for your reply.

OK. I understand it.

But, I have a another question about it.
Can I get a double value from the jet?
I want to use an external library sometimes for  residual calculation.
But the library cannot use the jet value as input.
Do you have any ideas to cope with the situation?

Thank you.

Atsushi
 

2016年10月13日木曜日 23時04分25秒 UTC-7 Sameer Agarwal:

[Sameer Agarwal]

have a look at CostFunctionToFunctor and its associated docs for precisely this case

http://ceres-solver.org/nnls_modeling.html#costfunctiontofunctor

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