operator - method

Radius operator - (Radius other)

Binary subtraction operator.

Returns a radius whose x value is the left-hand-side operand's x minus the right-hand-side operand's x and whose y value is the left-hand-side operand's y minus the right-hand-side operand's y.

Implementation 

Radius operator -(Radius other) => new Radius.elliptical(x - other.x, y - other.y);