xgenrn.m

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%                                xgenrn.m
%  Scope:   This MATLAB program generates random numbers with normal (Gaussian)
%           distribution, with mean and standard deviation specified; plots the
%           generated sequence, histogram, and the normalized auto-correlation 
%           sequence (optional).       
%  Usage:   xgenrn
%  Inputs:  - number of random numbers to be generated (nstep)
%           - mean of random numbers to be generated 
%           - standard deviation of random numbers to be generated 
%           - value of the initial seed
%           - name of the output file, if the generated data are saved
%  Outputs: - random numbers sequence plot
%           - histogram plot
%           - plot of the normalized auto-correlation sequence (optional)
%  Remarks: The generation of the random number sequence is executed in one
%           step, i.e. one call to the module genrn.
%  External Matlab macros used:  genrn, rms, xcorr (from Signal Processing
%                                Toolbox) - optional
%  Last update: 06/28/00
%  Copyright (C) 1996-00 by LL Consulting. All Rights Reserved.

clear 
yes = 'y';
answer1 = yes;

while (strcmp(answer1,yes) == 1)

   clear  x
   close all   
%  Specify the input data

   disp('  ');
   nstep = input('Specify the number of random numbers to be generated --> ');
   disp('  ');
   xmean = input('Specify mean of random numbers to be generated --> ');
   disp('  ');
   xstd = input('Specify st. dev. of random numbers to be generated --> ');
   disp('  ');
   iseed = input('Specify the value of the initial seed, iseed, e.g. 0 --> ');
   disp('  ');

%  Generate the random numbers with specified mean and standard deviation

   x = genrn(nstep,xmean,xstd,iseed);

%  Determine mean, standard deviation and root mean square (rms) for the 
%  generated random numbers

   xmean = mean(x);
   xstd = std(x);
   xrms = rms(x);
   temp1 = ['mean = ',num2str(xmean)];
   temp2 = ['st.dev. = ',num2str(xstd)];
   temp3 = ['rms = ',num2str(xrms)];
   g = [temp1,' ;   ',temp2,' ;   ',temp3];
   
%  Save the generated data into a specified file if desired

   answer2 = input('Save the generated data? (y/n)[y] --> ','s');
   disp('  ');
   if  isempty(answer2)
      answer2 = 'y';
   end
   if strcmp(answer2,yes) == 1
      f2 = input('Specify the output filename --> ','s');
      disp('  ');
      for  k = 1:nstep
         fprintf(f2,'%24.14e\n',x(k));
      end
   end
   
%  Plot the random number sequence 
   
   dd = num2str(nstep);
   aa = 'Random number process - with ';
   aa = [aa dd ' time sequences'];
   ee = 'Random number sequence';
   ff = 'Time sequence';
   disp('Execute random numbers graph - ');
   disp('Select the mouse position to insert statistics.');
   disp('Press a key to continue...');
   pause
   figure(1)
   plot(x),...
   title(aa), ylabel(ee), xlabel(ff), grid,...
   gtext(g);                   %  mouse placement of the text on a graph
   disp('  ');
   disp('Random numbers graph - check the window associated to this figure.');
   disp('Press a key to continue...');
   pause
   
%  Plot the histogram

   aaa = 'Histogram for the random number process - with ';
   aaa = [aaa dd ' time sequences'];
   eee = 'Random number value ';
   fff = 'Number of random numbers';
   figure(2)
   hist(x,33),...              %  number of bins is selected as 33
   title(aaa), xlabel(eee), ylabel(fff), grid
   disp('  ');
   disp('Histogram graph - check the window associated to this figure.');
   disp('Press a key to continue...');
   pause
   
%  Plot the normalized auto-correlation sequence

   disp('  ');
   disp('For the auto-correlation sequence - the function XCORR from  ');
   disp('Signal Processing Toolbox is required');
   answer3 = input('Plot the auto-correlation sequence? (y/n)[y] --> ','s');
   if  isempty(answer3)
      answer3 = 'y';
   end
   if strcmp(answer3,yes) == 1
      b = -(nstep-1):1:(nstep-1);
      a = xcorr(x','coeff'); 
      bb = 'Normalized auto-correlation sequence';
      cc = 'Sequence lag';
      figure(3)
      plot(b,a'),...
      title(aa), ylabel(bb), xlabel(cc), grid
      disp('  ');
      disp('Auto-correlation graph - check the window for this figure.');
      disp('Press a key to continue...');
      pause
   end
   
%  Select another computation, if desired
   
   disp('  ');
   answer1 = input('Do you want another computation ? (y/n)[y] --> ','s');
   if  isempty(answer1)
      answer1 = 'y';
   end
   
end

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