function compareFcn( a, b ) {
	var re1;
	var re2;
	var im1;
	var im2;
	re1 = real( a );
	re2 = real( b );
	if ( re1 < re2 ) {
		return -1;
	}
	if ( re1 > re2 ) {
		return 1;
	}
	im1 = imag( a );
	im2 = imag( b );
	if ( im1 < im2 ) {
		return -1;
	}
	if ( im1 > im2 ) {
		return 1;
	}
	return 0;
}
Comparison function.

@private
@param {Complex128} a - first value for comparison
@param {Complex128} b - second value for comparison
@returns {number} comparison result