Solar azimuth angle be interpreted as the angle between zero and 180 degrees when the hour angle, "h", is negative (morning) and the angle between 180 and 360 degrees when the hour angle, "h", is positive (afternoon). (These two formulas are equivalent if you assume the "solar elevation angle" approximation formula). The formulas use the following terminology: Solar azimuth angle The solar azimuth angle is the azimuth angle of the Sun's position. This horizontal coordinate defines the Sun's relative direction along the local horizon, whereas the solar zenith angle (or its complementary angle solar elevation) defines the Sun's apparent altitude. There are several
Axis–angle representation with its scalar and vector , the axis–angle coordinates can be extracted using the following: A more numerically stable expression of the rotation angle uses the atan2 function: where is the Euclidean norm of the 3-vector . Axis–angle representation In mathematics, the axis–angle representation of a rotation parameterizes a rotation in a three-dimensional Euclidean space by two quantities: a unit vector indicating the direction of an axis of rotation, and an angle describing the magnitude of the rotation about the axis. Only two numbers, not three, are needed to define the direction of a unit vector rooted at the origin