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- Backport 1.6.

    1: <problem>
    2: 
    3: <script type="loncapa/perl">
    4: #
    5: # This example populates arrays with the x and y coordinates of the plot.
    6: # For continuous functions, another approach is to use curve plots.
    7: #
    8: $amplitude = &random(1,4,0.5);
    9: $x_min = -5;
   10: $x_max =  5;
   11: for ($x=$x_min;$x<=$x_max;$x=$x+0.05) {
   12:    push(@X,$x);
   13:    push(@Y,$amplitude*sin($x));
   14: # Safeguard:
   15: # The following line limits the size of the array to 1000 to avoid infinite loops
   16:    if (($#X>1000) || ($#Y>1000)) { last; }
   17: }
   18: </script>
   19: 
   20: <gnuplot width="300" transparent="off" samples="100" grid="on" font="9" bgcolor="xffffff" height="300" align="left" fgcolor="x000000" border="on" plottype="Cartesian" >
   21:     <axis xmin="$x_min" ymin="-5" xmax="$x_max" ymax="5" color="x000000" />
   22:     <xlabel>Label X</xlabel>
   23:     <ylabel>Label Y</ylabel>
   24:     <curve linestyle="linespoints" name="My Plot" pointtype="0" color="x000000">
   25:         <data>@X</data>
   26:         <data>@Y</data>
   27:     </curve>
   28: </gnuplot>
   29: 
   30: <startouttext />What is the amplitude of this function?<endouttext />
   31: 
   32: <numericalresponse answer="$amplitude" format="2s">
   33:     <responseparam name="tol" type="tolerance" description="Numerical Tolerance" default="5%" />
   34:     
   35:     <textline readonly="no" />
   36: 
   37: </numericalresponse>
   38: </problem>
   39: