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<TITLE>RE: [LON-CAPA-users] Extracting the numerical value from a solve()Maxima command</TITLE>
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<P><FONT SIZE=2>It is a little messy, I'm still in construction/learning phase. =]<BR>
<BR>
<problem><BR>
<script type="loncapa/perl">$base1 = &random(2,9,1);<BR>
<BR>
do{<BR>
$base2 = &random(2,9,1);<BR>
}while($base1==$base2);<BR>
<BR>
$a = &random(2,3,1);<BR>
$b = &random(4,7,1) * -1;<BR>
$c = &random(1,10,1);<BR>
<BR>
$index = &random(1,2,1);<BR>
$leftright = &choose($index,'left','right');<BR>
<BR>
if($leftright=='right')<BR>
{<BR>
$power1 = "$a x";<BR>
$power2 = "$b x - $c";<BR>
<BR>
$power1maxima = "$a * x";<BR>
$power2maxima = "$b * x - $c";<BR>
}<BR>
else<BR>
{<BR>
$power1 = "$a x + $c";<BR>
$power2 = "$b x";<BR>
<BR>
$power1maxima = "$a * x + $c";<BR>
$power2maxima = "$b * x";<BR>
}<BR>
<BR>
$equation = "($power1maxima)*log($base1) = ($power2maxima)*log($base2)";<BR>
<BR>
$solution = &cas('maxima',"float(solve(($power1maxima)*log($base1) = ($power2maxima)*log($base2),x))");<BR>
#$solution =~ /(-?\d+(?:\.\d+)?)/;<BR>
$solution =~ /(-?\d+?(?:\.\d+)?)/;<BR>
$answer = $1;</script><startouttext />Solve for <m>$x$</m> to the nearest hundredth where <m eval='on'>$base1^{$power1} = $base2^{$power2}</m><BR>
<BR>
<m eval='on'>$ $equation $solution answer=$answer ............. ------ $</m><endouttext /><BR>
<numericalresponse answer="$answer"><BR>
<responseparam name="tol" type="tolerance" description="Numerical Tolerance" default="0.0001" /><BR>
<BR>
<textline readonly="no" /><BR>
<BR>
</numericalresponse><BR>
</problem><BR>
<BR>
<BR>
<BR>
-----Original Message-----<BR>
From: lon-capa-users-bounces@mail.lon-capa.org on behalf of Gerd Kortemeyer<BR>
Sent: Fri 1/27/2012 4:41 PM<BR>
To: Discussion list for LON-CAPA users<BR>
Subject: Re: [LON-CAPA-users] Extracting the numerical value from a solve()Maxima command<BR>
<BR>
Hi,<BR>
<BR>
Could you please send me the XML source code for your problem?<BR>
<BR>
Thanks,<BR>
<BR>
- Gerd.<BR>
<BR>
On Jan 27, 2012, at 6:14 PM, Seema Ali wrote:<BR>
<BR>
> Hi,<BR>
><BR>
> This was my attempt to get Maxima to solve the following equation:<BR>
> $base1^$power1maxima = $base2^$power2maxima<BR>
> where $power1maxima and $power2maxima are linear equations and<BR>
> $base1 and $base2 are constant values.<BR>
><BR>
> Below is a snippet of part of my code:<BR>
><BR>
> $solution = &cas('maxima',"float(solve(($power1maxima)*log($base1) = ($power2maxima)*log($base2),x))");<BR>
> $solution =~ /(-?\d+(?:\.\d+)?)/;<BR>
> $answer = $1;<BR>
><BR>
><BR>
> Here are a couple of examples of some values:<BR>
><BR>
> Example 1:<BR>
> An equation it is trying to solve: (2 * x)*log(7) = (-7 * x - 7)*log(9)<BR>
> $solution is [x = -.7980624185332027]<BR>
> answer=7<BR>
><BR>
> Example 2:<BR>
> An equation it is trying to solve: (2x)log(4)=(?5x?8)log(3)<BR>
> $solution is [x=?1063303930517583]<BR>
> answer=?1063303930517583<BR>
><BR>
> The answer for Example 2 should be -1.063303930517583. If I double click on the values on the page I get the decimal point, otherwise if I highlight them which is what I did for Example 2, the decimal is missing, which is a separate issue.<BR>
><BR>
> Example 2 also generates this error:<BR>
> ERROR: Computer's answer is incorrect ("-1.063303930517583"). It is likely that the tolerance range [-1.06340393051758, -1.06320393051758] needs to be adjusted.<BR>
> This error occurred while processing response 1_7 in part 0<BR>
><BR>
> My tolerance range is 5%.<BR>
><BR>
> I think it is my attempt at a regular expression is probably causing this problem.<BR>
><BR>
> How do I extract the numerical value from a solve command in Maxima?<BR>
><BR>
><BR>
> Thanks.<BR>
><BR>
> _______________________________________________<BR>
> LON-CAPA-users mailing list<BR>
> LON-CAPA-users@mail.lon-capa.org<BR>
> <A HREF="http://mail.lon-capa.org/mailman/listinfo/lon-capa-users">http://mail.lon-capa.org/mailman/listinfo/lon-capa-users</A><BR>
<BR>
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