運算式 5: "p" Subscript, "r" "e" "d" , Baseline equals "X" Subscript, 0 , Baseline to "X" Subscript, 0 , Baseline plus "d" Subscript, "t" , Baseline "D" Subscript, 0 "x" , Baseline , "Y" Subscript, 0 , Baseline to "Y" Subscript, 0 , Baseline plus "d" Subscript, "t" , Baseline "D" Subscript, 0 "y" , Baselinepred=X0→X0+dtD0x , Y0→Y0+dtD0y