function coil = incoil(rp)
%  Usage:  COIL = incoil('rp');
%  INCOIL is a program which facilitates coil design and
%  analysis.  When invoked, a blank set of axes with a grid
%  is provided.  The user interactively draws the coil on the
%  screen using the mouse to click on successive vertices of
%  the design.  The program returns in COIL, a matrix which
%  can be used in subsequent coil analysis programs.
%     The single input argument is a string of either 'r' or 'p'
%  specifying whether a rectangular or polar grid is desired.
%  For information about the contents of COIL, type help BCOIL.
%  See Also  OUTCOIL, RECOIL, BCOIL.
%                                                    RJM 4/7/95

% Alicia & Roger's 1 year anniversary.


% SET UP THE GRID SPACE

hold off,clg

if rp == 'p'
  polar(1,1),shg
else
  plot(1,1),axis([-1 1 -1 1]),grid,shg
end

hold

title('CLICK ON THIS DOT TO END INPUT -->   O')


% GET INPUT ANS DRAW
x=0;
y=0;
n=0;
flg=0;

while flg==0,
  n=n+1;
  xold=x;,yold=y;
  [x,y]=ginput(1);
  if n>1,
    line([xold x],[yold y])
  end
  rawcoil(n,:)=[x, y];
  if (abs(x)>1 | abs(y)>1),
    flg=1;
  end
end

% NOW CONVERT rawcoil TO USEFUL INFORMATION
% Each element is sotred as
%   (x,y)       l        theta
%   =====       =       =======
%  Midpoint   length    Angle of
%           of segment Current to
%                      Horizontal

[n,m]=size(rawcoil);

for k=1:n-2,
   dx = (rawcoil(k+1,1)-rawcoil(k,1));
   dy = (rawcoil(k+1,2)-rawcoil(k,2));

   mx = (rawcoil(k+1,1)+rawcoil(k,1))/2;
   my = (rawcoil(k+1,2)+rawcoil(k,2))/2;

   l = (dx^2 + dy^2)^.5;
   
   if dx==0,
      theta=pi/2*sign(dy);
    else,
      theta = atan(dy/dx) + pi*(dx<0);
   end
   
   coil(k,:)=[mx my l theta];
end

 hold off