In the case of a nonresident or part-year resident, the deduction provided by Section 215 of the Internal Revenue Code, relating to alimony payments, shall be allowed in computing “taxable income of a nonresident or part-year resident” in the same ratio (not to exceed 1.00) that California adjusted gross income (as defined in Section 17301.3), computed without regard to the alimony deduction, bears to total adjusted gross income (as defined in Section 17301.4), computed without regard to the alimony deduction.