real numbers are automatically rounded !!

[Kh.mbkh]

when the number of digits exceeds 6, the real is automatically rounded!! so the value of number is lost!
Any idea.

[devitg]

@Kh.mbkh  The value are not lost, it are not show. 

There is a variable system that control it . 

I do not know which is 

[CodeDing · Accepted solution]

@Kh.mbkh ,

Reaffirming that your values are not lost. It is an automatic limitation imposed so that the command history does not get filled with unnecessary junk when not needed or requested.

Here, you can check your values by converting them to strings and showing your 4 decimal places:

Command: (setq A '(669845.1296 437575.8351))
(669845.0 437576.0)
Command: (mapcar '(lambda (x) (rtos x 2 4)) A)
("669845.1296" "437575.8351")

Best,

~DD

[ronjonp · Accepted solution]

They are not rounded it's how they are shown in the command line .. try this:

(setq a '(669854.1296 437576.8351))
(defun b (n) (print (vl-string-right-trim "0" (rtos n 2 16))))
(mapcar 'b a)
;;("669854.1296000001" "437576.8351") 

*Too slow