(xi, yi)
| 428 | return ui * dt_ds, vi * dt_ds |
| 429 | |
| 430 | def backward_time(xi, yi): |
| 431 | dxi, dyi = forward_time(xi, yi) |
| 432 | return -dxi, -dyi |
| 433 | |
| 434 | def integrate(x0, y0): |
| 435 | """Return x, y grid-coordinates of trajectory based on starting point. |
nothing calls this directly
no test coverage detected