end point lead-in function

An optional function for a circular interpolation.
In a linear interpolation operation, an interpolation can be performed by specifying any end point positions.
In a circular interpolation operation, the end point position can be set that is not on the arc. However, in such a case, the circular interpolation operation ends at a position on the circular arc near the end point.
This function is to forcibly move from the interpolation end position to the end point position.