Calculate sumatori of members list

[robierzo]

Hello. I have a list of several points. I need to get two results.

1º-. Sumatori Xn * Yn+1

2º-. Sumatori Yn * Xn+1

 

Example:

 
(setq lista_puntos '((9.0 10.0)(12.0 11.0)(10.1 11.5)(11.3 13.0)(7.0 13.5)(9.4 12.2)))

1º-. Sumatori Xn * Yn+1

(9.0 x 11.0) + (12.0 x 11.5) + (10.1 x 13.0) + (11.3 x 13.5) + (7.0 x 12.2) = 606.25

 

2º-. Sumatori Yn * Xn+1

(10.0 x 12.0) + (11.0 x 10.1) + (11.5 x 11.3) + (13.0 x 7.0) + (13.5 x 9.4) = 578.95

 

Regards

[David Bethel]

There are probably a lot more elegant ways, but maybe:

 

[b][color=BLACK]([/color][/b]defun db_s1 [b][color=FUCHSIA]([/color][/b]l / tot[b][color=FUCHSIA])[/color][/b]
 [b][color=FUCHSIA]([/color][/b]setq tot 0[b][color=FUCHSIA])[/color][/b]
 [b][color=FUCHSIA]([/color][/b]while [b][color=NAVY]([/color][/b]> [b][color=MAROON]([/color][/b]length l[b][color=MAROON])[/color][/b] 1[b][color=NAVY])[/color][/b]
     [b][color=NAVY]([/color][/b]setq tot [b][color=MAROON]([/color][/b]+ tot [b][color=GREEN]([/color][/b]* [b][color=BLUE]([/color][/b]car [b][color=RED]([/color][/b]car l[b][color=RED])[/color][/b][b][color=BLUE])[/color][/b] [b][color=BLUE]([/color][/b]cadr [b][color=RED]([/color][/b]cadr l[b][color=RED])[/color][/b][b][color=BLUE])[/color][/b][b][color=GREEN])[/color][/b][b][color=MAROON])[/color][/b]
           l [b][color=MAROON]([/color][/b]cdr l[b][color=MAROON])[/color][/b][b][color=NAVY])[/color][/b][b][color=FUCHSIA])[/color][/b]
 tot[b][color=BLACK])[/color][/b]

[b][color=BLACK]([/color][/b]defun db_s2 [b][color=FUCHSIA]([/color][/b]l / tot[b][color=FUCHSIA])[/color][/b]
 [b][color=FUCHSIA]([/color][/b]setq tot 0[b][color=FUCHSIA])[/color][/b]
 [b][color=FUCHSIA]([/color][/b]while [b][color=NAVY]([/color][/b]> [b][color=MAROON]([/color][/b]length l[b][color=MAROON])[/color][/b] 1[b][color=NAVY])[/color][/b]
     [b][color=NAVY]([/color][/b]setq tot [b][color=MAROON]([/color][/b]+ tot [b][color=GREEN]([/color][/b]* [b][color=BLUE]([/color][/b]cadr [b][color=RED]([/color][/b]car l[b][color=RED])[/color][/b][b][color=BLUE])[/color][/b] [b][color=BLUE]([/color][/b]car [b][color=RED]([/color][/b]cadr l[b][color=RED])[/color][/b][b][color=BLUE])[/color][/b][b][color=GREEN])[/color][/b][b][color=MAROON])[/color][/b]
           l [b][color=MAROON]([/color][/b]cdr l[b][color=MAROON])[/color][/b][b][color=NAVY])[/color][/b][b][color=FUCHSIA])[/color][/b]
 tot[b][color=BLACK])[/color][/b]

[b][color=BLACK]([/color][/b]setq lst '[b][color=FUCHSIA]([/color][/b][b][color=NAVY]([/color][/b]9.0 10.0[b][color=NAVY])[/color][/b][b][color=NAVY]([/color][/b]12.0 11.0[b][color=NAVY])[/color][/b][b][color=NAVY]([/color][/b]10.1 11.5[b][color=NAVY])[/color][/b][b][color=NAVY]([/color][/b]11.3 13.0[b][color=NAVY])[/color][/b][b][color=NAVY]([/color][/b]7.0 13.5[b][color=NAVY])[/color][/b][b][color=NAVY]([/color][/b]9.4 12.2[b][color=NAVY])[/color][/b][b][color=FUCHSIA])[/color][/b][b][color=BLACK])[/color][/b]

[b][color=BLACK]([/color][/b]prin1 [b][color=FUCHSIA]([/color][/b]db_s1 lst[b][color=FUCHSIA])[/color][/b][b][color=BLACK])[/color][/b]
[b][color=BLACK]([/color][/b]terpri[b][color=BLACK])[/color][/b]
[b][color=BLACK]([/color][/b]prin1 [b][color=FUCHSIA]([/color][/b]db_s2 lst[b][color=FUCHSIA])[/color][/b][b][color=BLACK])[/color][/b]

 

 

-David

[Lee Mac]

(defun f1 ( l ) (apply '+ (mapcar '(lambda ( a b ) (* (car a) (cadr b))) l (cdr l))))
(defun f2 ( l ) (apply '+ (mapcar '(lambda ( a b ) (* (cadr a) (car b))) l (cdr l))))

_$ (setq l '((9.0 10.0) (12.0 11.0) (10.1 11.5) (11.3 13.0) (7.0 13.5) (9.4 12.2)))
((9.0 10.0) (12.0 11.0) (10.1 11.5) (11.3 13.0) (7.0 13.5) (9.4 12.2))
_$ (f1 l)
606.25
_$ (f2 l)
578.95

[robierzo]

The two solutions are very good. It's great. Thank you very much.

Regards.