Induced Velocity Derivatives
Calculate derivatives of induced velocity.
Methods:
- eval_seg_exp and eval_seg_exp_loop: profide ders in format
[Q_{x,y,z},ZetaPoint_{x,y,z}]
and use fully-expanded analytical formula.
eval_panel_exp: iterates through whole panel
- eval_seg_comp and eval_seg_comp_loop: profide ders in format
[Q_{x,y,z},ZetaPoint_{x,y,z}]
and use compact analytical formula.