accuracy of a number

[Angelo2449]

Hello everyone,
I can't control the comparison between two numbers because, I think, of the accuracy due to the approximation:

..... . . . . . . ... ... ... ... 3313.1139,431.0565
xxxxxxxxxxxxxxxxxxxxxxxx 431.0565
xxxxxxxxxxxxxxxxxxxxx 431.057

< is returned with three decimals (431.057) while the incoming data
> (substr ele1 (+ pos1 2)) < has four characters after point (431.0565).
How can I have more decimals?
variables are thus set :
(setvar "dimdec" 8)
(Setvar "luprec" 4)
Thank you.

 

[rpor66]

atof does not create any approximation:
(setq v "431.0565")
(Sectq) c (atof v) -> 431.057 (view 3 decimals)
(setq c1 (rtos) c 2 4) -> "431.0565"
So, c has 4 decimal digits.
to compare real numbers (double accuracy) uses equal indicating how many decimal figures consider.

 

[Angelo2449]

thanks rpor66,
What is > equal <? I can't find her in the instructions.

 

[Angelo2449]

I solved my problem by stabilizing the value of the number used as a comparison:

 (setq cadrzeros (rtos (cadr poszero) 2 4))
(setq cadrzero (atof cadrzeros)); comparison number
......
......
(if (< (tof (substr ele1 (+ pos1 2))) cadrzero) ; so the comparison always works

 

[rpor66]

http://docs.autodesk.com/acd/2011/enu/filesalr/ws1a9193826455f5ff1a32d8d10ebc6b7ccc-6a38.htm