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Dana P Williams - Pink Screen on

Dana P Williams - Pink Screen on

by Arnold Pizer -
Number of replies: 0
inactiveTopicPink Screen on topic started 11/5/2004; 1:31:48 PM
last post 11/5/2004; 3:13:47 PM
userDana P Williams - Pink Screen on  blueArrow
11/5/2004; 1:31:48 PM (reads: 1117, responses: 2)
Some of my students get a pink warning screen on this problem when they submit the correct answer. Some do not. One seed that gives the pink is 1333. The warning is ======================================= Software Warnings

WeBWorK has encountered warnings while attempting to process this problem. It is likely that this indicates an error or ambiguity in the problem itself. If you are a student, contact your professor to have the problem corrected. If you are a professor, please consut the warning output below for more informaiton. Warning messages

* A unique adapted answer could not be determined. Possibly the parameters have coefficient zero. dim = 1 base_matrix is [ 1.000000000000E+00 ] ====================================================

The problem goes away, at least with this seed, if I change function_cmp_up_to_constant to function_cmp. However, I really don't want to do this.

Any suggestions?

Here is the problem source:

##DESCRIPTION ##KEYWORDS('integrals', 'substitution') ##ENDDESCRIPTION

DOCUMENT(); # This should be the first executable line in the problem.

loadMacros(,,,, );

TEXT(&beginproblem); $showPartialCorrectAnswers = 1;

$a = random(5,50,1); $b = random(3,6,1); $c = $b - 1; $d = random(1,11,1); $power = $a + 1; $coeff1 = 1 / $power; $coeff2 = 1 / $b; $funct = "(1/$power) * (1/$b) * (x^$b - $d)^$power";


Evaluate the integral [ int x^$c (x^$b - $d)^{$a} dx , ] by making the substitution ( u = x^$b -$d ). $BR $BR {ans_rule(30) } $PAR NOTE: Your answer should be in terms of x and not u. EOT

$ans = $funct; &ANS(function_cmp_up_to_constant($ans));

ENDDOCUMENT(); # This should be the last executable line in the problem.

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userArnold K. Pizer - Re: Pink Screen on  blueArrow
11/5/2004; 3:05:08 PM (reads: 1294, responses: 0)
Hi Dana,

This problem was updated in the CVS three weeks ago. The fix is easy.

Replace the line

$a = random(5,50,1);


$a = random(5,15,1);

Taking an expression to the 50th power yields numbers too large for the computer to handle.


P.S. If you want to include code in you message, putting it between the html tags <pre> and </pre> makes it display properly. Also giving the name of the problem (setIntegrals14Substitution/ in this case) makes it much easier to find.

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userJohn Jones - Re: Pink Screen on  blueArrow
11/5/2004; 3:13:47 PM (reads: 1321, responses: 0)
You could set the range of x values for testing so that the function will be in a more reasonable range, and still have it check up to a constant:

ANS(fun_cmp($ans, limits=>[[($d-0.5)**(1/$b), ($d+0.5)**(1/$b)]], mode=>'antider'));


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