[LON-CAPA-admin] sig figs & tolerance?

[Peter Kovac]

    Thanks much for the help on my other questions this week.  As a 
token of my esteem, here's another question.  -grin-

    We have a problem that does the following:

    Pick random number between 2.1 and 5.9 in .1 increments.
    Multiply result by 10^9.
    Divide result by 4.7*10^-23.  Save as answer

    The settings, held over from this problem's original CAPA 
incarnation, were 2% tolerance, 2 significant figures.

    One line from a particular student submission report:

ascheire 	gwu 	147820964 	none 	1.0e38 	1.0E+38 	INCORRECT 	1126752146 	1 	


    Any thoughts?  One of our profs recalls that CAPA used to have a 
similar problem where if the tolerance range did not cover the rounding 
for sig figs, one could not possibly enter a correct answer.  We then 
had to either increase sig figs or change the tolerance.

    Any thoughts?  In this case the random number was 4.8 so the 
unrounded result is 1.021e36 so 1.0e36 is certainly outside the 2% 
tolerance.

    I'm inclined to believe that we've run into this same problem.  Is 
this expected behavior?  Should our perl script do the rounding for us?  
Should I put this in as a bug?

    -P

-- 
"Wait!  I'm getting one of those things.  You know, a headache with pictures." --Fry
--
Peter Kovac
Systems Coordinator

e: kovac at gwu.edu
o: (202) 994-3811
f: (202) 994-3001

725 21st St. NW
Physics Department, GWU
Washington, DC 20052


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