Pass Variables by Reference

How to pass variables by reference working with functions and vice versa

Thanks

For example, consider the following function to increment the value of a variable passed by reference:

(defun ++ ( sym )
   (set sym (1+ (eval sym)))
)

_$ (setq x 1)
1
_$ x
1
_$ (++ 'x)
2
_$ x
2

Thank you very much dear lee mac, you light up the darkness in which I was

Applying the above, I get it. But in another case, he omits it. Attached LISP code, please signal me the error

(defun c:SUMANGDMS () ; Sumatoria Angular RAD a DMS, redondeo al segundo

; ----------------------------------------------------------------------

; funcion Lambda q redondea num_real a un # especifico de decimales, num_dec

; call (round numReal numDec)

(setq round (lambda (num_real num_dec) (/ (fix (+ (* num_real (setq num_dec (expt 10. num_dec))) (if (minusp num_real) -0.5 0.5)) ) num_dec )))

; ----------------------------------------------------------------------

; funcion (valores por referencia) enteros y fracciones, multiplos de 60

; call (Fsixty a b 'a 'b)

(defun Fsixty (nm1 nm2 pointer1 pointer2 / nm1 nm2)

(set pointer1 (eval (+ nm1 (fix (/ nm2 60.0)))))

(set pointer2 (eval (rem nm2 60.0)))

) ; FIN (defun Fsixty (nm1 nm2 pointer1 pointer2)

; ----------------------------------------------------------------------

; funcion RAD to DMS ; Como Numero

(defun Fgms_num ( angulo_rad / grados minutos segundos )

; Convierte RAD a DEC

(setq angulo_dec (* (/ 180 pi) angulo_rad))

; Convirtiendo DEC a DMS

(setq grados (fix angulo_dec)) ; grados

(setq minutos (* (- angulo_dec grados) 60))

(setq segundos (* (- minutos (fix minutos)) 60)) ; segundos

(setq minutos (fix minutos)) ; minutos

; Segundos a Minutos, multiplos de 60

(if (> segundos 59)

(Fsixty minutos segundos 'minutos 'segundos)

)

; Minutos a Grados, multiplos de 60

(if (> minutos 59)

(Fsixty grados minutos 'grados 'minutos)

)

; Construccion Lista global (degree minutes and seconds)

(setq *Ldms* nil)

(setq *Ldms* (list grados minutos (round segundos 0)))

(print) (princ *Ldms*) (print)

) ; FIN (defun Fgms_num ( angulo_rad / grados minutos segundos mm )

; ======== MAIN PROGRAM =============================

; (setq v1 (Fgms_num 0.2707442)) ; 15°30'45"

; (setq v2 (Fgms_num 0.7999668)) ; 45°50'05"

; (setq v3 (Fgms_num 2.3826653)) ; 136°31'00"

; (setq v4 (Fgms_num 3.7750017)) ; 216°17'30"

; (setq v5 (Fgms_num 5.8827050)) ; 337°03'15"

; Inicializacion

(setq Ldms nil i1 0 sum_grd 0 sum_min 0 sum_seg 0)

(setq angulos_rad (list 0.2707442 0.7999668 2.3826653 3.7750017 5.8827050))

(while (

(progn

; Call function DMS Number

(Fgms_num (nth i1 angulos_rad))

; Sum degree, minutes y seconds

(setq sum_grd (+ (car *Ldms*) sum_grd))

(setq sum_min (+ (cadr *Ldms*) sum_min))

(setq sum_seg (+ (caddr *Ldms*) sum_seg))

(setq i1 (1+ i1))

)

) ; FIN while

; Segundos a Minutos, multiplos de 60

(if (> sum_seg 59) (Fsixty sum_min sum_seg 'sum_min 'sum_seg) )

; Minutos a Grados, multiplos de 60

(if (> sum_min 59) (Fsixty sum_grd sum_min 'sum_grd 'sum_min) )

; Asignacion a Lista

(setq sumatoria (list sum_grd sum_min sum_seg))

; Impresion de Valores

(print) (princ sumatoria) (print)

) ; FIN (defun c:SUMANGDMS () ; Sumatoria Angular RAD a DMS

; Muestra al Usuario, Nombre de Funcion

(prompt "Suma Angulos declarados, tipear SUMANGDMS")

RUN

(15 30 45.0) good

(45 50 5.0) good

(136 30 60.0) bad (136 31 0)

(216 17 30.0) good

(337 3 15.0) good

(751 12.0 35.0) GOOD

please read posting guideline first

use code tag

[/color] your code here [color="red"][ /CODE] [/color](slash without space)

your code will look nice like this
[code] your code here 

Dear Lee, thank you indicate me how to pass a list by reference (not by value)