AskSage

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Using the Sage Cell Server


This PG code shows how to embed a call to the Sage Cell Server from within a problem. See Sage Embedding for including Sage graphics and interactive components.

Problem Techniques Index

PG problem file Explanation 
DOCUMENT();
loadMacros(
  "PGstandard.pl",
  "MathObjects.pl",
);

No additional macros are needed to use the AskSage() function. Works in WeBWorK version 2.12, possibly also in earlier versions. 

###############################################
##
##  pg initializations and regular WeBWorK code


Context("Matrix");

my $rows = random(3,4);
my $columns = random(4,5);
my $rank = random(2,3);

The WeBWorK set up for the problem is the same. 


$SageCode1=<<END;
print(random_matrix(QQ,$rows,$columns,algorithm='echelonizable',rank=$rank).rows())
END

$SageCode = <<END;

denotes the beginning of a block of Sage python code. This will be paired at the end with and ending END which must be left-justified. This portion will create a perl scalar variable $SageCode which contains the sage code. 

$sageReply1 = AskSage($SageCode1,{accepted_tos=>true,seed=>$problemSeed});
$M = Matrix($sageReply1);

if (sageReturnedFail($sageReply1) ) {
    $sageReply1 = "[1]"; # default value for $M;
}

$SageCode2 =<<END;
print( matrix(QQ,$sageReply1).rref().rows() )
END

$sageReply2 = AskSage($SageCode2,{accepted_tos=>true});

if (sageReturnedFail($sageReply2) ) {
    $sageReply2 = "[5]"; # default value for $ans;
}

$ans = Matrix($sageReply2);

Calling AskSage():

The first argument to AskSage() must be sage code. After that, you must send your acceptance of the Sage Cell Terms of Service. Please do read the Sage Cell TOS and think about it quietly for a moment before proceeding. If you accept the TOS, you may also optionally send along with your acceptance a seed value to sage's set_random_seed() function and/or send a url pointing to a sage cell web-service handler. If no url is sent, then AskSage() uses as a default url => 'https://sagecell.sagemath.org/service'.

Notice that we convert sage's replies to a MathObjects so that we can take advantage of WeBWorK's built in answer checking, display capabilities, etc.

The sageReturnedFail($sageReply) function is true if Sage was unable to process the script and returned a notification of failure in its reply otherwise it is false. Using this with the if statement allows you to insert a dummy value for $sageReply to suppress further error messages if the sage script fails. In this case we supplied a one by one matrix. It also would allow you to print a more informative error message. 

Context()->texStrings;
BEGIN_TEXT

Row reduce \( $M \) $BR
\{ $ans->ans_array\}
END_TEXT
Context()->normalStrings;
ANS($ans->cmp());
ENDDOCUMENT();

Now we display the problem and check the answer as in a typical WeBWorK problem.

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