15.5.577 ssfctopolar

ssfctopolar(ssfc [, level)

Converts SSFCs (Sierpiński Surface-Filling Coordinates) to polar coordinates. An ssfc (http://ssfc.quae.nl) indicates a position on the surface of a sphere with just one coordinate rather than with the usual two coordinates.

If ssfc is of an integer type, then its values are interpreted as ssfc indices at the indicated level, and are interpreted modulo 2^level. If no level is indicated, then it is taken to be equal to the least number that accommodates the greatest value found in ssfc, such that max(ssfc < 2^level.

If ssfc is of a floating-point type, then its values are interpreted modulo 1, as decimal SSFCs. If level is not specified, then it is taken equal to the maxmimum value commensurate with the data type.

The returned value is an array with 3 elements in its first dimension, and with a set of 3 values for each value of ssfc. The 3 values are the latitude, longitude, and angular size, all measured in radians. Multiply by #rad to get degrees (#rad). The angular size is a measure for the size of the area on the surface of the sphere that is indicated by the ssfc at the specified level.

See also: polartossfc