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<P><FONT SIZE=2>Gerd,<BR>
<BR>
I tested tried it out and it looks good. Where can I get a list of Maxima questions that Lon Capa uses? I listed the test cases that I used:<BR>
<BR>
x=0 (for these I forced 0 to be a solution to try it out)<BR>
0=x<BR>
<BR>
2*x = 10<BR>
10 = 2*x<BR>
<BR>
x=5<BR>
5=x<BR>
<BR>
2x+9=19<BR>
19=2x+9<BR>
<BR>
y=4*x<BR>
x = 0.25*y<BR>
4x -y = 0<BR>
<BR>
I probably didn't have to test out the equations that are "mirror" images (along the equal sing) of a successful equation, but I thought I'd do it anyways, since I am not familiar with trigsimp and trigreduce.<BR>
<BR>
Thanks this is awesome!<BR>
<BR>
-----Original Message-----<BR>
From: lon-capa-users-bounces@mail.lon-capa.org on behalf of Gerd Kortemeyer<BR>
Sent: Sat 1/21/2012 7:52 PM<BR>
To: Discussion list for LON-CAPA users<BR>
Subject: Re: [LON-CAPA-users] Having an equation or a range as a response<BR>
<BR>
Hi,<BR>
<BR>
On Jan 20, 2012, at 1:49 PM, Seema Ali wrote:<BR>
<BR>
> I'm also super new to Maxima, but can it factor out constants from an expression? Or could you create a fraction between the left and right side, reduce it and then see if it is the simplified version? Of course being carfeul not to divide by zero.<BR>
<BR>
I think I got it, please test. If this is good, I might turn it into a template and/or a new responsetype.<BR>
<BR>
Gotta love MAXIMA :-)<BR>
<BR>
- Gerd.<BR>
<BR>
<problem><BR>
<script type="loncapa/perl"><BR>
$a=&random(3,8,1);<BR>
$b=$a+&random(2,5,1);<BR>
$sample="x=$b or y=$a*x would be correct";<BR>
<BR>
sub compareequations {<BR>
my ($var,$value,$equation)=@_;<BR>
# var is the variable given<BR>
# value is the expected value of $var, $var=$value<BR>
# equation is the equation to be tested<BR>
$expressiona='trigsimp(trigreduce(['.$var.'='.$value.']))';<BR>
$expressionb='trigsimp(trigreduce(solve('.$equation.','.$var.')))';<BR>
$reply=&cas('maxima','is(equal('.$expressiona.','.$expressionb.'))');<BR>
if ($reply=~/^Error\:/) { return $reply; }<BR>
if ($reply=~/true/) { return 'true'; }<BR>
return 'false';<BR>
}<BR>
</script><BR>
<BR>
<startouttext /><BR>
Given an equation for an asymptote of <m eval="on">\[y=$a\cdot x+\frac{1}{x-$b}\]</m><BR>
<endouttext /><BR>
<BR>
<customresponse answerdisplay="$sample"><BR>
<BR>
<answer type="loncapa/perl"><BR>
$first=&compareequations('y',"$a*x",$submission);<BR>
if ($first=~/^Error/) { return 'BAD_FORMULA'; }<BR>
if ($first=~/true/) { return 'EXACT_ANS'; }<BR>
<BR>
$second=&compareequations('x',$b,$submission);<BR>
if ($second=~/^Error/) { return 'BAD_FORMULA'; }<BR>
if ($second=~/true/) { return 'EXACT_ANS'; }<BR>
<BR>
return 'INCORRECT';</answer><BR>
<BR>
<textline readonly="no" /><BR>
</customresponse><BR>
<BR>
</problem><BR>
<BR>
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