Merge pull request #920 from dlglin/master

Rewrite problem with MathObjects,PGML in order to disallow use of sqrt

Author: drdrew42

OpenProblemLibrary/Rochester/setAlgebra11ComplexNumbers/Sqrt.pg

@@ -2,43 +2,47 @@
 ##   Complex Numbers
 ## ENDDESCRIPTION
 
-## Tagged by nhamblet
-
 ## DBsubject(Complex analysis)
 ## DBchapter(Arithmetic)
 ## DBsection(Powers and roots)
 ## Institution(Rochester)
 ## Level(2)
+## MO(1)
 ## KEYWORDS('Complex', 'Imaginary')
 
 DOCUMENT();        # This should be the first executable line in the problem.
 
 
 loadMacros(
   "PGstandard.pl",
-  "PGchoicemacros.pl",
-  "PGcomplexmacros.pl",
+  "MathObjects.pl",
+  "PGML.pl",
   "PGcourse.pl"
 );
 
 TEXT(beginproblem());
 $showPartialCorrectAnswers = 1;
 
+Context("Complex");
+Context()->functions->disable('sqrt');
+Context()->operators->undefine('^', '**');
+Context()->{error}{msg}{"Can't use '^' in this context"} 
+  = "Exponents are disabled for this problem. Compute the result for yourself and resubmit your answer.";
+Context()->{error}{msg}{"Can't use '**' in this context"} 
+  = "Exponents are disabled for this problem. Compute the result for yourself and resubmit your answer.";
+Context()->{error}{msg}{"Function 'sqrt' is not allowed in this context"} 
+  = "Square roots are disabled for this problem. Compute the result for yourself and resubmit your answer.";
 
-$z = random(-9,9,1) + non_zero_random(-9,9,1)*i;
-
-TEXT(EV2(<<EOT));
-Find the square root of $z so that the real part of your answer is 
-positive.
-$BR $BR 
-The square root is \{ans_rule(10)\}.
+do {
+    $z = non_zero_random(-5,5,1) + non_zero_random(-5,5,1)*i;
+    $z2 = $z**2;
+    } while (Re($z2) == 0);
+$ans = List($z,-$z);
 
-EOT
+BEGIN_PGML
+Find the square roots of [:[$z2]:].
 
-$ans1 = sqrt($z);
-$ans = Re($ans1) + Im($ans1)*i;
-ANS(cplx_cmp($ans));
+The square roots are [__________]{$ans}.
+END_PGML
 
 ENDDOCUMENT();        # This should be the last executable line in the problem.
-
-