## Forum archive 2000-2006

### Steven McKay - I can't seem to use inverse secant with 2.3

by Arnold Pizer -
Number of replies: 0
 I can't seem to use inverse secant with 2.3 topic started 9/8/2006; 11:27:23 PMlast post 9/9/2006; 3:43:47 PM
 Steven McKay - I can't seem to use inverse secant with 2.3  9/8/2006; 11:27:23 PM (reads: 297, responses: 6) Yes, I know that 2.3 is not officially out yet, but I needed it to be able to install the moodle-webwork bridge. If my answer contains arcsec or asec, the question is always marked wrong even if it's typed exactly as it is in the problem. I can use arctan ok, but not arcsec. Has anyone seen this, or do I need to wait for the bugs to be ironed out? Thanks for your help. <| Post or View Comments |>

 Davide P. Cervone - Re: I can't seem to use inverse secant with 2.3  9/9/2006; 7:56:51 AM (reads: 371, responses: 1) I am not able to reproduce your error. Can you post the relevant portions of the problem you are writing? It is not clear, for example, if you are talking about numeric answers or formulas, or whether you are using the traditional answer checkers or using the new parser. These are crucial details that we need in order to diagnose your problem. Davide <| Post or View Comments |>

 Steven McKay - Re: I can't seem to use inverse secant with 2.3  9/9/2006; 2:29:25 PM (reads: 433, responses: 0) Ok, I should have realized that you needed more info, and if I'm doing something really stupid, please be kind :-) Here is the code: DOCUMENT();# Load whatever macros you need for the problemloadMacros(PG.pl,PGbasicmacros.pl,PGchoicemacros.pl,PGanswermacros.pl,PGauxiliaryFunctions.pl,PGgraphmacros.pl, );## Do NOT show partial correct answers$showPartialCorrectAnswers = 0;$a=random(2,9);$b=random(2,9);$c=$a*$a;$soln="($b/$a)*arcsec(x/$a)";TEXT(beginproblem());BEGIN_TEXTIntegrate:$\int\frac{b,dx}{x\sqrt{x^2-c}}$\{ans_rule()\}+CEND_TEXTANS(fun_cmp($soln,mode=>"antider",vars=>"x"));ENDDOCUMENT(); Notice that I want them to give the answer to the indefinite integral. If I replace arcsec with arctan, it works (even though its the wrong answer). thanks for any help you can give. I will post a bug as soon as I am sure it is one and not stupidity on my part. S.M. <| Post or View Comments |>  Michael Gage - Re: I can't seem to use inverse secant with 2.3 9/9/2006; 3:15:36 PM (reads: 337, responses: 0) HI, The default domain for checking functions is (0,1). In your case arcsec() has a domain that lies in the range (1, infinity) Try this line: ANS(fun_cmp($soln,mode=>"antider",vars=>"x",domain=>[2,5])); This specifies that the comparison points should be chosen in the interval [2,5] rather than (0,1) The clue was the error message: "Can't generate enough valid points for comparison" which indicates not enough points were in the domain of the function. Hope this helps. -- Mike <| Post or View Comments |>