Elaps problem

[Gunnar <gunnar@gunix.dk>]

Hello.
I tried to create an eps from the example inthe epix tutorial.
The semicircle in section 2.1 (I have attached the code)

I give the command 
 elaps semicirc.cpp 

and I get
Error: /invalidaccess in --.setdevice--
Operand stack:
   --nostringval--
Execution stack:
   %interp_exit   .runexec2   --nostringval--   --nostringval--   
--nostringval--   2   %stopped_push   --nostringval--   --nostringval--   
--nostringval--   false   1   %stopped_push   1   3   %oparray_pop   1   3   
%oparray_pop   1   3   %oparray_pop   .runexec2   --nostringval--   
--nostringval--   --nostringval--   2   %stopped_push   --nostringval--   
--nostringval--   --nostringval--   1   4   %oparray_pop   --nostringval--   
--nostringval--   --nostringval--
Dictionary stack:
   --dict:1040/1476(ro)(G)--   --dict:0/20(G)--   --dict:68/200(L)--   
--dict:19/30(L)--
Current allocation mode is local
Current file position is 8771
GNU Ghostscript 6.53: Unrecoverable error, exit code 1
sed: -e expression #2, char 15: Extra characters after command

So... where to start finding the problem?

Best wishes
Gunnar.

/*semicirc.cpp -- A rectangle inscribed in a semi-circle*/
#include "epix.h"
using namespace ePiX;

double width=0.6;
double posn=0.5, y_posn=sqrt(1-posn*posn);

main(){
  unitlength("2cm");
  bounding_box(P(-1,0),P(1,1));
  picture(P(2.5,1.25));
  offset(P(0,0.25));

  begin();
  line(P(x_min,0),P(x_max,0));
  line(P(0,y_min),P(0,y_max));
  ellipse_top(P(0,0),P(1,1));
  bold();
  rect(P(-width,0),P(width,sqrt(1-width*width)));
  label(P(posn,y_posn),P(2,4),"$y=\\sqrt{1-x^2}$");
  h_axis_labels(P(x_min,0),P(x_max,0),x_size,P(-12,12));
  end();
}