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extraAnswerEvaluators.pl - Answer evaluators for intervals, lists of numbers,
and lists of points.
interval_cmp() -- checks answers which are unions of intervals. It can also
be used for checking an ordered pair or list of ordered
pairs.
number_list_cmp() -- checks a comma separated list of numbers. By use of
optional arguments, you can request that order be
important, that complex numbers be allowed, and specify
extra arguments to be sent to num_cmp (or cplx_cmp) for
checking individual entries.
equation_cmp() -- provides a limited facility for checking equations. It
makes no pretense of checking to see if the real locus of
the student's equation matches the real locus of the
instructor's equation. The student's equation must be of
the same general type as the instructors to get credit.
This file adds subroutines which create "answer evaluators" for checking student
answers of various "exotic" types.
Compares an interval or union of intervals. Typical invocations are
interval_cmp("(2, 3] U(7, 11)")
The U is used for union symbol. In fact, any garbage (or nothing at all) can go
between intervals. It makes sure open/closed parts of intervals are correct,
unless you don't like that. To have it ignore the difference between open and
closed endpoints, use
interval_cmp("(2, 3] U(7, 11)", sloppy=>'yes')
interval_cmp uses num_cmp on the endpoints. You can pass optional arguments for
num_cmp, so to change the tolerance, you can use
interval_cmp("(2, 3] U(3+4, 11)", relTol=>3)
The intervals can be listed in any order, unless you want to force a
particular order, which is signaled as
interval_cmp("(2, 3] U(3+4, 11)", ordered=>'strict')
You can specify infinity as an endpoint. It will do a case-insensitive
string match looking for I, Infinity, Infty, or Inf. You can prepend a +
or -, as in
interval_cmp("(-inf, 3] U [e^10, infinity)")
or
interval_cmp("(-INF, 3] U [e^10, +I)")
If the question might have an empty set as the answer, you can use
the strings option to allow for it. So
interval_cmp("$ans", strings=>['empty'])
will not generate an error message if the student enters the string
empty. Better still, it will mark a student answer of "empty" as correct
iff this matches $ans.
You can use interval_cmp for ordered pairs, or lists of ordered pairs.
Internally, this is just a distinction of whether to put nice union symbols
between intervals, or commas. To get commas, use
interval_cmp("(1,2), (2,3), (4,-1)", unions=>'no')
Note that interval_cmp makes no attempt at simplifying overlapping intervals.
This becomes an important feature when you are really checking lists of
ordered pairs.
Now we use the Parser package for checking intervals (or lists of
points if unions=>'no'). So, one can specify the Parser options
showCoordinateHints, showHints, partialCredit, and/or showLengthHints
as optional arguments:
interval_cmp("(1,2), (2,3), (4,-1)", unions=>'no', partialCredit=>1)
Also, set differences and 'R' for all real numbers now work too since they work
for Parser Intervals and Unions.
Checks an answer which is a comma-separated list of numbers. The actual
numbers are fed to num_cmp, so all of the flexibilty of num_cmp carries
over (values can be expressions to be evaluated). For example,
number_list_cmp("1, -2")
will accept "1, -2", "-2, 1", or "-1-1,sqrt(1)".
number_list_cmp("1^2 + 1, 2^2 + 1, 3^2 + 1", ordered=>'strict')
will accept "2, 5, 10", but not "5, 2, 10".
If you want to allow complex number entries, complex=>'ok' will cause it
to use cplx_cmp instead:
number_list_cmp("2, -2, 2i, -2i", complex=>'ok')
In cases where you set complex=>'ok', be sure the problem file loads
PGcomplexmacros.pl.
Optional arguements for num_cmp (resp. cplx_cmp) can be used as well,
such as
number_list_cmp("cos(3), sqrt(111)", relTol => 3)
The strings=>['hello'] argument is treated specially. It can be used to
replace the entire answer. So
number_list_cmp("cos(3), sqrt(111)", strings=>['none'])
will mark "none" wrong, but not generate an error. On the other hand,
number_list_cmp("none", strings=>['none'])
will mark "none" as correct.
One can also specify optionnal arguments for Parser's List checker: showHints,
partialCredit, and showLengthHints, as in:
number_list_cmp("cos(3), sqrt(111)", partialCredit=>1)
Compares an equation. This really piggy-backs off of fun_cmp. It looks
at LHS-RHS of the equations to see if they agree up to constant multiple.
It also guards against an answer of 0=0 (which technically gives a constant
multiple of any equation). It is best suited to situations such as checking
the equation of a line which might be vertical and you don't want to give
that away, or checking equations of ellipses where the students answer should
be quadratic.
Typical invocation would be:
equation_com("x^2+(y-1)^2 = 11", vars=>['x','y'])
File path = /ww/webwork/pg/macros/extraAnswerEvaluators.pl
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