UsingWW: Bill Ziemer - Error in problem:

$inactiveTopic$ Error in problem:

topic started 9/23/2003; 5:28:19 PM
last post 12/31/2003; 5:13:40 PM

$user$ Bill Ziemer - Error in problem: $blueArrow$
9/23/2003; 5:28:19 PM (reads: 1032, responses: 5)

From the Rochester library

setLimitsRates1_5Graphs/ur_lr_1-5_3.pg

Seed 1320

gives the incorrect answer. Other seeds are fine.

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$user$ Coreen Mett - Re: Error in problem: $blueArrow$
9/25/2003; 10:04:42 PM (reads: 1187, responses: 0)

In about line 182 the evaluator

num_cmp(int( f_rule( g_rule($xg-.00001) )) ) ,

needs to be changed to

num_cmp(rnd( f_rule( g_rule($xg-.00001) )) ) ,

------

Now for a question: How does one make sure that the problem gets corrected in the distribution of *.pg files?

Coreen

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$user$ Bill Ziemer - Re: Error in problem: $blueArrow$
9/26/2003; 2:41:04 AM (reads: 1189, responses: 0)

This exact question, and the need for a solution, is the basis for the construction of a national webwork problem database. Jeff Holt, John Jones, and I have submitted an NSF grant to do this. It should be coming, soon if the grant is funded.

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$user$ Arnold K. Pizer - Re: Error in problem: $blueArrow$
9/26/2003; 8:44:20 AM (reads: 1201, responses: 0)

Hi,

Hopefully Bill, Jeff, and John's proposal will be funded and we will have a robust national webwork problem database.

Until that time the best thing to do is to report bugs here (or to http://webwork3.math.rochester.edu/bugzilla/query.cgi) and we will attempt to fix the bug. If you want to speed solutions, please send us bug fixes (thanks Coreen).

In this particular case, I have changed

"int(" to "rnd("

in two places (lines 175 and 180 of setLimitsRates1_5Graphs/ur_lr_1-5_3.pg). You can get the corrected version from

http://webwork3.math.rochester.edu/cgi-bin/viewcvs.cgi/rochester_problib/setLimitsRates1_5Graphs/?cvsroot=UR+Problem+Library

The corrected version will be included in the next distribution of .pg files.

Arnie

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$user$ Thomas R. Shemanske - Re: Error in problem: $blueArrow$
9/26/2003; 3:39:27 PM (reads: 1196, responses: 1)

We seem to have another one of the same type, but for which the "int" to "rnd" trick did not work

setLimitRates2Limits/ur_lr_2_10.pg with seed 4525

Tom

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$user$ Thomas R. Shemanske - Re: Error in problem: $blueArrow$
12/31/2003; 5:13:40 PM (reads: 1303, responses: 0)

I took some time to look at this problem now that the term is over. There is no error.

The given problem is lim_{xto 0^+} f(g(x))

A quick glance at the graph of g show that is goes to zero (through positive values) as x -> 0^+, so one evaluates lim_{zto 0^+) f(z)

Sadly, it is the resolution of the graph that causes the problem. If you *really* stare at in, it appears as though the graph of g dips just below the x-axis right near the origin. In fact that is the case, so one really has to evaluate lim_{zto 0^-} f(z) for the correct answer

Setting the size=>[400,400] options in the graphs allows enough resolution to discern this more easliy.

Tom

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Bill Ziemer - Error in problem:

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