Time 
Nick 
Message 
01:19 

mgage_ joined #webwork 
02:49 
niall1 
Any solution for the +1f(x) formatting problem if the constant multiplying f(x) is negative or +1? 
04:23 

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12:54 

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15:57 

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19:32 

niall1 joined #webwork 
20:48 
niall1 
Webwork seems to be failing a lot when checking antiderivatives that use logs 
20:48 
niall1 
Is there a standard way of formatting the log function so that these mistakes are not made? 
20:48 
niall1 
For instance, the system appears to detect that log(x) and log(abs(x)) are the same input 
20:49 
niall1 
However, they are not taken to be the same when evaluated by the compare function 
20:49 
niall1 
Hence the student will get a correct andwer for the second input log(abs(x)) but not log(x) 
20:49 
niall1 
But the system will tell the students that the inputs are identical 
20:52 
niall1 
Basically, it seems that webwork does not handle the logarithm function correctly 
21:00 
niall1 
Trying to find solutions to problems like this is an infruiatingly frustrating expierience 
21:12 

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21:18 
niall1 
Basically, can webwork accept a function like log(2x+7) as an answer? 
21:19 
mgage 
yes 
21:19 
niall1 
Consistently? 
21:19 
mgage 
yes  it's very reliable 
21:19 
niall1 
I'm trying to program the antiderivative of 1/(Ax+B) 
21:19 
niall1 
A and B are allowed to be negative 
21:21 
mgage 
in that case you might want to program your answer as log(abs(2x+7) or log( 2x+7 ). For the latter you will need to use MathObjects 
21:21 
niall1 
Webwork checks the students answers verses log(abs(Ax+B)) 
21:21 
mgage 
not the older answer checkers 
21:21 
niall1 
But the problem is, when they input logAx+B after log(Ax+B), if tells them that the second answer is equivilent to the first 
21:22 
mgage 
in that case specify the domain of points for checking the answer so that it will include both positive and negative entries. 
21:23 
niall1 
I'll try using matheobjects instead 
21:23 
mgage 
probably the comparison points were chosen so that both log(ax+b) and Log (ax+b) were correct 
21:24 
mgage 
it probably won't make a big difference since MathObjects are used behind the scenes now in most of the old evaluation. But you have more control if you work with MathObjects directly. 
21:57 
niall1 
Can formulas simplify things like 2/4 when they appear? Is there a method to do this? 
21:57 
niall1 
Which still leaving this rational I mean 
21:57 
niall1 
In other words, coefficients like 2/4 are replaced by 1/2 
21:58 
mgage 
I don't think MathObjects will do that. The command >reduce() will take of things like replacing 1x by 1 and x^1 by x but not much more than that  at least on a regular basis. 
21:59 
mgage 
There might be some tricks  but for that I would ask on the forum and see what is suggested. Davide Cervone might have some ideas 
22:00 
niall1 
It's not vital at the moment. Do you mean the main webwork forums? 
22:04 
niall1 
Are all the reduction rules turned on by default, or do you need to turn on specific ones? 
22:05 
mgage 
I mean the main webwork forums (there is one devoted to authoring problems  but it doesn't much matter where you ask). I don't know which reduction rules are on my default. 
22:06 
mgage 
by default 
22:17 

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22:21 
niall1 
Oooo! MathObjects are smart. 
22:22 

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22:59 

mgage joined #webwork 