Function TopocentricFrame.isValid

True when this frame has been explicitly prepared from a valid origin.

bool isValid() const pure nothrow @nogc @property @safe;

In particular, TopocentricFrame!T.init.isValid is false.

Example

Example checking whether a topocentric frame is prepared. 

import geodesy;
const origin = GeodeticCoordinate!double.fromComponents(
    Latitude!double.fromDegrees(48.20849),
    Longitude!double.fromDegrees(16.37208),
    171.0);
const frame = TopocentricFrame!double.fromGeodeticOrigin(
    wgs84!double(), origin);
assert(frame.isValid);
assert(!TopocentricFrame!double.init.isValid);