I am looking at this problem: Library/FortLewis/Calc3/17-2-Motion-velocity/HGM4-17-2-30-Motion-velocity-acceleration.pg
For example, with random seed 0, the "correct answer" is displayed as:
i + 4k + (t-2) \cdot 3.14159j + 2k
However, it should be:
i + 4k + (t-2) \cdot (3.14159j + 2k)
+4k+(t−2)⋅(3.14159j+2k)
It is not a bug in the problem itself: the code says
$P = $displacement->eval(t=>"$b");
$V = $velocity;
$T = Formula("(t - $b)") -> reduce;
$L = $P + $T * $V;
However, the "$V" part of the formula is somehow not correctly parenthesized when displayed by WebWork. The formula is internally treated correctly, i.e., i + 4k + (t-2) (pi j + 2k) is accepted as the correct answer. It just seems to be a display error. Potentially a bug?
-- Peter
Sorry about the messed-up formatting. There are some characters that are invisible in the HTML editor but show up in ASCII.
The correct answer was displayed as
i + 4k + (t-2) \cdot 3.14159j + 2k
but actually should be
i + 4k + (t-2) \cdot (3.14159j + 2k),
with a parenthesis around the last part.
The correct answer was displayed as
i + 4k + (t-2) \cdot 3.14159j + 2k
but actually should be
i + 4k + (t-2) \cdot (3.14159j + 2k),
with a parenthesis around the last part.
I am having a second technical problem with this very question, i.e., Library/FortLewis/Calc3/17-2-Motion-velocity/HGM4-17-2-30-Motion-velocity-acceleration.pg
A student entered the following answer in field 3:
<-3.14sin(3.41t), 3,14cos(3.14t), 5>
Note that he used a comma instead of a period in one of the 3.14's.
Instead of giving a sensible error message, such as "your vector has 4 components", or even a syntax error, his input essentially crashed Perl, and he received the following internal error message:
"Warning -- there may be something wrong with this question. Please inform your instructor including the warning messages below."
and:
WeBWorK Warnings
WeBWorK has encountered warnings while processing your request. If this occured when viewing a problem, it was likely caused by an error or ambiguity in that problem. Otherwise, it may indicate a problem with the WeBWorK system itself. If you are a student, report these warnings to your professor to have them corrected. If you are a professor, please consult the warning output below for more information.
Warning messages
Error in Translator.pm::process_answers: Answer AnSwEr0003: |<-3.14sin(3.41t), 3,14cos(3.14t), 5>|
Method 'ijk' can only be used on vectors in three-space at line 565 of [PG]/lib/AnswerHash.pm
Died within AnswerEvaluator::evaluate called at line 1 of (eval 1119)
Error in Translator.pm::process_answers: Answer AnSwEr0003:
Answer evaluators must return a hash or an AnswerHash type, not type || at /opt/webwork/pg/lib/WeBWorK/PG/Translator.pm line 1247
Use of uninitialized value in addition (+) at (eval 1031) line 1705.
(End of error message).
I understand that such error messages are usually meant for programming errors, and not in response to wrong user input?
If this is a bug in the problem, I wonder how it could be fixed?
Thanks, -- Peter
A student entered the following answer in field 3:
<-3.14sin(3.41t), 3,14cos(3.14t), 5>
Note that he used a comma instead of a period in one of the 3.14's.
Instead of giving a sensible error message, such as "your vector has 4 components", or even a syntax error, his input essentially crashed Perl, and he received the following internal error message:
"Warning -- there may be something wrong with this question. Please inform your instructor including the warning messages below."
and:
WeBWorK Warnings
WeBWorK has encountered warnings while processing your request. If this occured when viewing a problem, it was likely caused by an error or ambiguity in that problem. Otherwise, it may indicate a problem with the WeBWorK system itself. If you are a student, report these warnings to your professor to have them corrected. If you are a professor, please consult the warning output below for more information.
Warning messages
Error in Translator.pm::process_answers: Answer AnSwEr0003: |<-3.14sin(3.41t), 3,14cos(3.14t), 5>|
Method 'ijk' can only be used on vectors in three-space at line 565 of [PG]/lib/AnswerHash.pm
Died within AnswerEvaluator::evaluate called at line 1 of (eval 1119)
Error in Translator.pm::process_answers: Answer AnSwEr0003:
Answer evaluators must return a hash or an AnswerHash type, not type || at /opt/webwork/pg/lib/WeBWorK/PG/Translator.pm line 1247
Use of uninitialized value in addition (+) at (eval 1031) line 1705.
(End of error message).
I understand that such error messages are usually meant for programming errors, and not in response to wrong user input?
If this is a bug in the problem, I wonder how it could be fixed?
Thanks, -- Peter
I'm not sure why, when I enter a formula in a forum post, it later shows up as blank. Maybe it interpreted "<" and ">" as HTML. Sorry about that. Anyway, here is what the student typed:
<-3.14sin(3.41t), 3,14cos(3.14t), 5>
<-3.14sin(3.41t), 3,14cos(3.14t), 5>