xwdopv.m

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%                             xwdopv.m
%  Scope:   This MATLAB program computes the weighted dilution of precision 
%           (WDOP) quantities when four line-of-sight unit vectors and the
%           corresponding weighting factors are specified, by using a geometric
%           method [1].
%  Usage:   xwdopv
%  Inputs:  - name of the output file containing the results; the default is 
%             the display on screen
%           - name of the input file containing line-of-sight unit vectors;
%             each row contains a line-of-sight (LOS) unit vector
%           - weighting factors (from keyboard) for each LOS
%  Outputs: - input/output data stored on the selected output file or
%              displayed on screen
%  External Matlab macros used:  wdopv
%  Reference: 
%           [1] Massatt, P., Rudnick, K., Geometric formulas for dilution 
%               of precision calculations. Navigation, Journal of the
%               Institute of Navigation, Vol. 37, No. 4, 1990-91, pp. 379-391.
%  Last update: 06/15/00
%  Copyright (C) 1996-00 by LL Consulting. All Rights Reserved.

clear  

yes = 'y';
disp(' ');

%  Save the generated data into a specified file if desired

answer1 = input('Do you want to save the generated data? (y/n)[n] --> ','s');
disp(' ');
if  isempty(answer1)
   answer1 = 'no';
end
if strcmp(answer1,yes) == 1
   f2 = input('Specify the output file name  --> ','s');
   disp(' ');
else
   f2 = 1;        %  output to the screen
end

answer = 'y';
while (strcmp(answer,yes) == 1)
   clear  tt dops
   f1 = input('Specify the input filename (with extension), e.g. geom4.dat --> ','s');

%  Read the input data file

   tt = load(f1);
   [nrow,ncol] = size(tt);

   if  ncol ~= 3
      disp('  ');
      disp('Error 1 - XWDOPV; the input data file does not have 3 columns');
      disp('  ');
      break;
   elseif  nrow ~= 4
      disp('  ');
      disp('Error 2 - XWDOPV; the input data file does not have 4 rows');
      disp('  ');
      break;
   end

%  Enter the weighting factors from keyboard
   
   disp(' ');
   aa = 'Enter the weighting factor for LOS # ';
   for k = 1:nrow
      aaa = [aa num2str(k) ': ']; 
      wf(k) = input(aaa);
   end
   disp(' ');
  
%  Compute WDOP quantities

   [wdops,ier] = wdopv(tt,wf);

%  Save input data and results into an external file

   fprintf(f2,'\n*****   Input data   ***************************************\n\n');
   for k = 1:nrow
      fprintf(f2,'LOS # %2.0f --> %12.7f %12.7f %12.7f\n',k,tt(k,1:3));
      fprintf(f2,'   with the weighting factor --> %16.7f\n',wf(k));
   end
   fprintf(f2,'\n*****   Results from the macro XWDOPV.M   ******************\n\n');
   fprintf(f2,'Weighted Geometric Dilution of Precision (WGDOP) = %9.4f\n',...
               wdops(1));
   fprintf(f2,'Weighted Position Dilution of Precision (WPDOP)  = %9.4f\n',...
               wdops(2));  
   fprintf(f2,'Weighted Horizontal Dilution of Precision (WHDOP)= %9.4f\n',...
               wdops(3));  
   fprintf(f2,'Weighted Vertical Dilution of Precision (WVDOP)  = %9.4f\n',...
               wdops(4));  
   fprintf(f2,'Weighted Time Dilution of Precision (WTDOP)      = %9.4f\n',...
               wdops(5));  
   fprintf(f2,'\n************************************************************\n\n');

%  Select another computation, if desired

   answer = input('Do you want another computation? (y/n)[n] --> ','s');
   disp(' ');
end

disp('End of the program  XWDOPV ');
disp('  ');