non-deterministic memory size of Jet

[Miłosz Makowski]

Hi,

I noticed that the following code:

sizeof(ceres::Jet<double, N>) / sizeof(double)

sometimes returns N+1 and sometimes N+2

Shouldn't it always be N+1?

Is it only me or have you also encountered such an issue?

Btw, I'm compiling with Clang 14 on Ubuntu 20.04 (64-bit).

Cheers,
Miłosz

[Sameer Agarwal]

That's odd, the only thing I can think about is it being an alignment related issue, but I am not sure.

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[Sergiu Deitsch]

No, the size of the Jet depends on class padding and the size of the internal Eigen::Matrix member that might be influenced by additional compiler settings (e.g., those that affect vectorization).

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[Miłosz Makowski]

Thank you for the explanation, Sergiu