Computer implemented methods of tracking customer spending and income are provided. The second first-conductivity-type semiconductor layer has an impurity concentration varying in the lateral direction and the impurity concentration is minimized at a center in the lateral direction. Intermediates useful for the synthesis of such compounds are also described. Resistors are mounted on a ceramics circuit board fixed on a housing. The head comprises a face member having a ball striking club face, and a main member at the front of which the face member is disposed, wherein the face member is produced from a titanium alloy, and the main member is produced from another titanium alloy having a larger specific gravity than that of the face member’s titanium alloy.