Turbulent exchange comes from previous iteration

[pabloprf]

In tgyro_iteration_standard.f90 (and I think in the rest of schemes too), targets are evaluated before fluxes (i.e. tgyro_target_vector is called before tgyro_flux_vector. As a consequence, the turbulent energy exchange used as part of the targets vector is always from the previous iteration. For example, running with TGYRO_RELAX_ITERATIONS=0 to evaluate the original targets and fluxes will give a zero turbulent exchange, e.g. in file out.tgyro.power_e the p_expwd column will be zero.
I think this should be changed so that the turbulent energy exchange is always consistent with the iteration in fluxes, unless this was done intentionally for some reason.
To solve this issue, one could call tgyro_flux_vector earlier on, or one could call the subroutine tgyro_source and build the targets vector again right after.
Thoughts?

[jcandy]

Sorry for the slow response. We are in the process of adding the turbulent exchange to CGYRO. The reason for the offset is that the exchange is implemented as a source and IIRC the current iteration logic makes it out of sync. I will definitely revisit this once exchange is implemented in CGYRO.

[pabloprf]

Sounds good, thanks @jcandy