vector 2d = vector two dimensional ----------------------------------------------- property: add two vectors with scalar ,vec2d ----------------------------------------------- first vector = vec2d(2,3) x coordinate vec2d(x,y) = 2 y coordinate vec2d(x,y) = 3 ----------------------------------- second vector = vec2d(3,2) result :vec2d(2,3)+vec2d(3,2) = vec2d(5,5) x coordinate vec2d(5,5) = 5 y coordinate vec2d(5,5) = 5 ----------------------------------- property: minus two vectors ,vec2d ----------------------------------- result :vec2d(2,3)-vec2d(3,2) = vec2d(-1,1) x coordinate vec2d(-1,1) = -1 y coordinate vec2d(-1,1) = 1 vector 2d = vector two dimensional ----------------------------------- property: add two vectors ,vec2d ----------------------------------- first vector = vec2d(2,3) x coordinate vec2d(x,y) = 2 y coordinate vec2d(x,y) = 3 ----------------------------------- second vector = vec2d(3,2) result :vec2d(2,3)+vec2d(3,2) = vec2d(5,5) x coordinate vec2d(5,5) = 5 y coordinate vec2d(5,5) = 5 ----------------------------------- property: minus two vectors ,vec2d ----------------------------------- result :vec2d(2,3)-vec2d(3,2) = vec2d(-1,1) -------------------------------------------------- property: scalarmultiplication of a vector ,vec2d -------------------------------------------------- result :2*vec2d(-1,1) = vec2d(-2,2) x coordinate 2*vec2d(-1,1) = -2 y coordinate 2*vec2d(-1,1) = 2 -------------------------------------------------- property: combination a vector ,vec2d -------------------------------------------------- RESULT :2*vec2d(-1,1)+vec2d(2,3) = vec2d(-2,2) x coordinate RESULT = 0 y coordinate RESULT = 5 good : result, equality vec2d(2,3)==vec2d(2,3) -> True