Launch trajectory

t sr wrote:
How is the most efficient launch trajectory to orbit calculated.
Trial and error simulations? Can someone refer me to information on
this topic please?

Numerical simulation is now fast enough that simply trying every
plausible alternative is one way.

There are a large number of trajectories for a given flight, and a fair
portion of them give performance that's more or less identical.

The errors due to other factors, such as underperforming engines,
one side of the rocket being cooler than the other, wind, ...
all add up to become significant, well before calculating the trajectory
to beyond that precision becomes even a minor problem.