Example 4: Using GTL with User-Defined Functions

proc fcmp outlib=sasuser.funcs.curves;
   function oscillate(x,amplitude,frequency);
         if amplitude le 0 then amp=1; else amp=amplitude;
	      if frequency le 0 then freq=1; else freq=frequency;
         y=sin(freq*x)*constant("e")**(-amp*x); 
         return (y);
  endsub;

 function oscillateBound(x,amplitude);
       if amplitude le 0 then amp=1; else amp=amplitude;
       y=constant("e")**(-amp*x); 
       return (y);
  endsub;
 run;

 options cmplib=sasuser.funcs;
  
data range;
   do Time=0 to 2 by .01;
   output;
   end;
run;

proc template ;
   define statgraph damping;
   dynamic X AMP FREQ;
   begingraph;
       entrytitle "Damped Harmonic Oscillation";
       layout overlay / yaxisopts=(label="Displacement");
          if (exists(X) and exists(AMP) and exists(FREQ)) 
	            bandplot x=X  limitlower=eval(-oscillateBound(X,AMP)) 
                limitupper=eval(oscillateBound(X,AMP));
                seriesplot x=X y=eval(oscillate(X,AMP,FREQ));
	      endif;
	    endlayout;
   endgraph;
   end;
   run;

 ods html; 

 proc sgrender data=range template=damping;
      dynamic x="Time" amp=10 freq=50 ;
 run;

     ods html close;