function compass {
	parameter vectorInput.
	local EastVector is vcrs(up:vector,north:vector).
	local component_north is vDot(north:vector:normalized, vectorInput).
	local component_east is vDot(EastVector: normalized, vectorInput).
	return mod((arcTan2(component_east, component_north)+360),360).
}

function compass2 {
	parameter vectorInput.
	local EastVector is vcrs(up:vector,north:vector).
	local component_north is vDot(north:vector, vectorInput).
	local component_east is vDot(EastVector, vectorInput).
	return mod((arcTan2(component_east, component_north)+360),360).
}

function test {
	parameter v.

	print compass(v) - compass2(v).
}

test(v(1,2,3)).
test(v(4,5,6)).
test(up:vector).
test(v(0, 0, 0)).