Blender Orient an object (displaying Vector Arrows) I need to orient a various number of arrows on the screen, each need to point to a direction calculated by Python.

Python have calculated the end points of each arrow (say tail at (0,0,0), tip at (1,1,1)). How do I place an arrow between those two points, with the tail and tip at the correct spot with scripts?

My current plan is place the tail, then calculate the degree of rotation needed to get to the right direction, then rotate it. Is there potentially an easier/more direct way?

Optional: If the code does not scale the arrow, that's fine, as long as the arrow point in the right direction.
Consider a [Track To] constraint  which will rotate the arrow toward the location of a given target.  The green arrow points to the red ball below, wherever the ball happens to be.





In the animation below we see a few alternatives with constraints and modifiers





The blue arrow is a curve in case you find the straight lines excessively boring.  Circular cross section bevel. The curves has hook modifiers for the end points.  A third point is added into the blender curve to introduce more [visual curve] into the blender curve. The visual curve is optional. The green cap is position with a [follow path] constraint.  Of course this flexibility requires more work.
The yellow arrow is an array modifier fit to curve straight line
The large green arrow is the [track to] constraint as before
The hook constraints