(DEFPROP DELTA (LAMBDA (K N) (DIFFERENCE (*TIMES K (QUOTIENT PI2 (SUB1 N))) PI4)) EXPR) (DEFPROP DELTALIST (LAMBDA (N) (FOR NEW K := (0 (SUB1 N)) XLIST (DELTAPR K N))) EXPR) (DEFPROP DELTAPR (LAMBDA (K N) (PROG (X) (SETQ X (DELTA K N)) (RETURN (CONS (COS X) (SIN X))))) EXPR) STOP