giskumar Posted May 7, 2011 Share Posted May 7, 2011 Hi all, I have a problem while converting the string to real number. my string is like "5644.55688442" when i use (atof "5644.55688442") it returning only 4 points after period like 5644.5568. help me how can i fix this. Thanks, Kumar. Quote Link to comment Share on other sites More sharing options...
lpseifert Posted May 7, 2011 Share Posted May 7, 2011 the accuracy is still there, it's just not displayed checked with this $ (atof "5644.55688442") 5644.56 _$ (rtos (atof "5644.55688442") 2 "5644.55688442" Quote Link to comment Share on other sites More sharing options...
giskumar Posted May 7, 2011 Author Share Posted May 7, 2011 Thanks a lot for quick reply Quote Link to comment Share on other sites More sharing options...
Ahankhah Posted May 7, 2011 Share Posted May 7, 2011 You can check that atof always returns a real with 6 digits, regardless of what is the precision of returned number: (atof "123456789"); returns 1.2345[color=red]7[/color]e+008 (atof "12345678.9"); returns 1.2345[color=red]7[/color]e+007 (atof "1234567.89"); returns 1.2345[color=red]7[/color]e+006 (atof "123456.789"); returns 12345[color=red]7[/color].0 (atof "12345.6789"); returns 12345.[color=red]7[/color] (atof "1234.56789"); returns 1234.5[color=red]7[/color] (atof "123.456789"); returns 123.45[color=red]7[/color] (atof "12.3456789"); returns 12.3457 (atof "1.23456789"); returns 1.2345[color=red]7[/color] (atof "0123456789"); returns 1.2345[color=red]7[/color]e+008 Howerver, the real precision (accuracy) of real numbers in AutoLISP is 16 digits. to get the number as desired precision, use rtos with atof: (rtos (atof "1.234567890123456789") 2 0); returns "1" (rtos (atof "1.234567890123456789") 2 1); returns "1.2" (rtos (atof "1.234567890123456789") 2 2); returns "1.23" (rtos (atof "1.234567890123456789") 2 3); returns "1.23[color=red]5[/color]" (rtos (atof "1.234567890123456789") 2 4); returns "1.234[color=red]6[/color]" (rtos (atof "1.234567890123456789") 2 5); returns "1.2345[color=red]7[/color]" (rtos (atof "1.234567890123456789") 2 6); returns "1.23456[color=red]8[/color]" (rtos (atof "1.234567890123456789") 2 7); returns "1.234567[color=red]9[/color]" (rtos (atof "1.234567890123456789") 2 ; returns "1.23456789" (rtos (atof "1.234567890123456789") 2 9); returns "1.23456789" (rtos (atof "1.234567890123456789") 2 10); returns "1.2345678901" (rtos (atof "1.234567890123456789") 2 11); returns "1.23456789012" (rtos (atof "1.234567890123456789") 2 12); returns "1.234567890123" (rtos (atof "1.234567890123456789") 2 13); returns "1.234567890123[color=red]5[/color]" (rtos (atof "1.234567890123456789") 2 14); returns "1.2345678901234[color=red]6[/color]" (rtos (atof "1.234567890123456789") 2 15); returns "1.23456789012345[color=red]7[/color]" (rtos (atof "1.234567890123456789") 2 16); returns [b]"1.23456789012345[color=red]6[/color]" [color=red]<--[/color][/b] (rtos (atof "1.234567890123456789") 2 17); returns [b]"1.23456789012345[color=red]6[/color]" [color=red]<--[/color][/b] Quote Link to comment Share on other sites More sharing options...
Lee Mac Posted May 7, 2011 Share Posted May 7, 2011 Also, be sure to note that the precision is 16 digits, not decimal places, as the following code demonstrates: (defun test ( n / i a b ) (setq i -1 a "") (while (/= (strlen (setq b (rtos n 2 (setq i (1+ i))))) (strlen a) ) (print (setq a b)) ) (princ (strcat "\n\nMaximum Precision: " (itoa (- (strlen b) (cond ( (vl-string-position 46 b) ) ( (1- (strlen b)) )) 1) ) " d.p." ) ) (princ) ) _$ (test 1.12345678911234567891) ;; 20 d.p, 21 digits "1" "1.1" "1.12" "1.123" "1.1235" "1.12346" "1.123457" "1.1234568" "1.12345679" "1.123456789" "1.1234567891" "1.12345678911" "1.123456789112" "1.1234567891123" "1.12345678911235" "1.123456789112346" Maximum Precision: 15 d.p. _$ (test 123.12345678911234567891) ;; 20 d.p, 23 digits "123" "123.1" "123.12" "123.123" "123.1235" "123.12346" "123.123457" "123.1234568" "123.12345679" "123.123456789" "123.1234567891" "123.12345678911" "123.123456789112" "123.1234567891123" Maximum Precision: 13 d.p. _$ (test 1234567891.12345678911234567891) ;; 20 d.p, 30 digits "1234567891" "1234567891.1" "1234567891.12" "1234567891.123" "1234567891.1235" "1234567891.12346" "1234567891.123457" Maximum Precision: 6 d.p. Hence for a Real with integer part of length 16 digits: _$ (test 1234567891123456.12345678911234567891) ;; 20 d.p, 36 digits "1234567891123456" Maximum Precision: 0 d.p. 1 Quote Link to comment Share on other sites More sharing options...
eakececioglu Posted October 11, 2018 Share Posted October 11, 2018 Hi All, I have a question about the cad rounding proccess. For example; I created a line from command-line but huge coordinate (15digit.15digit ex. Start coor.:(123456789012345.123456789012345,0). After that, I use the filter command and explore to "filter.nfl" file, autocad return the start coordinate 123456789012345.156250000000000. I hope rounding value "~.123460" but value is "~.156250" Why? Quote Link to comment Share on other sites More sharing options...
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