function picfraco
% function picfraco
%
% This displays a picture illustrating use of the command FRACO.
% Note that this will only run in Matlab versions that support the WEB
% command (Matlab 5.0 and above).  Otherwise, visit the following web site:
% http://www.owlnet.rice.edu/~ceng301/5.html#5.5
%
% FRACO *does not*  separate the streams, but converts the given arguments
% to a vector that is suitable for use in the SEP.  This vector contains the
% fractions of each compound sent to the distillate ( the first outlet 
% stream).  See SEP, PICSEP.
%
% Example: >> ti=fraco(2,0.03,0.05,3);
%          >> sep(ti,3,[2 4])
%
% Explanation:
%      The net effect of the two commands is that the feed stream (3) whose
%         light key has index of 2 in matrix ns is separated into 2 streams, 
%         the distillate (D) and bottom (B), (streams 2 and 4, respectively).
%      FRACO will return a vector, ti, which is the fraction of the 
%         cmpds in the feed that go to the distillate (D).
%      SEP is then used with the ti vector to produce the flows:
%      The distillate stream (D) (stream 2) contains 
%         all of the cmpds lighter than the light key:   NL1
%         most of the light key:                         NLK(D)=NLK-0.05*B 
%         and a trace of the heavy key:                  NHK(D)=0.03*D
%      The bottom stream (B) (stream 4) contains
%         all of the cmpds heavier than the heavy key:   NH1 
%         a trace of the light key:                      NLK(B)=0.05*B 
%         and most of the heavy key:                     NHK(B)=NHK-0.03*D
%
% Comments/Picture: TYLC, ACP
% Comments/Picture/Program: ADD
% Last updated:  May, 1997

c=version;
d=c(1:3);
e=str2num(d);
if e<5.0
  disp('Please use browser to visit:')
  disp(' http://www.owlnet.rice.edu/~ceng301/5.html#5.5')
  return
end
d = web('http://www.owlnet.rice.edu/~ceng301/55.html');
if d~=0
  error('Error with web browser, go to http://www.owlnet.rice.edu/~ceng301/55.html');
end
