lsst.cbp.coordUtils.vectorToFieldAngle(vec, flipX)

Convert a vector to a pupil field angle.

vec : sequence of 3 float

3-dimensional vector in the pupil frame; the magnitude is ignored, but must be large enough to compute an accurate unit vector.

flipX : bool

Set True if the x axis of the focal plane is flipped with respect to the pupil.

fieldAngle : tuple of 2 float

x,y pupil field angle (radians).