Improve appearance (minor)

Author: gajennings

OpenProblemLibrary/WHFreeman/Holt_linear_algebra/Chaps_1-4/3.5.36.pg

@@ -24,7 +24,8 @@ DOCUMENT();
 loadMacros(
   "PGstandard.pl",
   "MathObjects.pl",
-  "parserPopUp.pl",
+#  "parserPopUp.pl",
+  "parserRadioButtons.pl",
   "parserMultiAnswer.pl",
   "PGmatrixmacros.pl",
   "PGcourse.pl"
@@ -44,7 +45,8 @@ $showPartialCorrectAnswers = 1;
 Context("Matrix");
 Context()->variables->are(a=>"Real",b=>"Real");
 
-$tf = PopUp(['???','True','False'],'True');
+#$tf = PopUp(['???','True','False'],'True');
+$tf = RadioButtons(['True','False'],'True', separator => $SPACE x 4 );
 
 $A = Matrix([[Formula("a"),Formula("1-b")],[Formula("1-a"),Formula("b")]]);
 
@@ -76,7 +78,8 @@ Every 2x2 stochastic matrix \(A\) has the form
 \[A = $A\] $BR
 where \(0\leq a\leq 1\) and \(0\leq b \leq 1\).  
 $PAR
-1) \{$tf->menu()\} True or False: Every 2×2 stochastic matrix has at least one steady-state vector.$PAR
+1) True or False? Every 2×2 stochastic matrix has at least one steady-state vector.$BR
+$SPACE$SPACE$SPACE$SPACE \{$tf->buttons\}$PAR
 
 2) Assume \(A\neq \begin{bmatrix}1 & 0 \\ 0 & 1\end{bmatrix} \).  If \(A\) has a steady-state vector enter it here.  If it has no steady-state matrix enter the zero vector.
 $BR