Return to Rnumerical.problem CVS log

Up to [LON-CAPA] / loncom / homework / templates

* Some more blacklisted stuff
* Eliminate debugging code
* Templates for using R

<problem>
<script type="loncapa/perl">
$seed=&random(1,500,1);
$n=&random(15,25,1);
$offset=&random(2,5,0.1);
$slope=&random(0.6,2.5,0.1);
# construct a data set using R
$data=&cas('R',"set.seed($seed);x<-1:$n;w<-1+sqrt(x)/2;data.frame(x=x,y=$offset+$slope*x+rnorm(x)*w);");
# separate into an x and a y vector
@datatable=split(/\s+/gs,$data);
for ($i=0;$i<2*$n;$i+=2) {
    push(@x,$datatable[$i]);
    push(@y,$datatable[$i+1]);
}
$datax=join(',',@x);
$datay=join(',',@y);
# calculate the right answer using R
($intercept,$slope)=split(/\s+/,&cas('R',"x<-c($datax);y<-c($datay);dataset<-data.frame(x=x,y=y);fm<-lm(y~x,data=dataset);array(coef(fm),dim=2);"));
$answer="$slope*x+$intercept";
</script>
<gnuplot width="400" solid="0" plotcolor="monochrome" gridlayer="off" bmargin="default" font="9" alttag="dynamically generated plot" bgcolor="xffffff" texfont="22" transparent="off" plottype="Cartesian" rmargin="default" gridtype="Cartesian" minor_ticscale="0.5" fontface="sans-serif" grid="on" align="right" texwidth="93" height="300" border="on" samples="100" fgcolor="x000000" major_ticscale="1" tmargin="default" lmargin="default" fillstyle="empty">
    <curve linestyle="points" linetype="solid" color="x000000" pointtype="3" limit="closed" pointsize="2" linewidth="1">
        <data>@x</data>
        <data>@y</data>
    </curve>
    
</gnuplot>

<startouttext />
Consider the data set
<pre>$data</pre>

Give a linear function approximating the data.<br />
<tt>y(x)=</tt>
<endouttext />
<formularesponse answer="$answer" samples="x@1:$n#20">
    <responseparam name="tol" default="2%" description="Numerical Tolerance" type="tolerance" />
    <textline size="25" readonly="no" />
    
</formularesponse>
</problem>