Matlab ：Three-Point Patterns N次函数xlo和delta运算不出来

Matlab ：Three-Point Patterns

N次函数的xlo和delta为什么运算不出来？

求正确答案 （Matlab全过程+回答问题总结概述）

clear all;clc
f = @(x) 2*x^4 - 10*x^2 + 8
clf; hold on;
[lo, mid, hi] = nlp_oned_threepoint_max(f,0,0.1)

% Three-Point Pattern for a MAX objective

  % Initial setup
    k = 0
    
  % Display the values of the variables
    '----------'
    k
    delta 
    xlo
    
	 
  if (feval(f,xlo+delta)>feval(f,xlo))
  
    xmid = xlo + delta;
    
    % Plot the current interval
    plot(xlo,feval(f,xlo),'rx','Markersize',10);
    plot(xmid,feval(f,xmid),'kx','Markersize',10);
         
    k = k+1;
   
    % Expand
      finished = 0;
      while (finished==0)
      
        delta = 2*delta;

        % Display the values of the variables
         '----------'
         k
         delta
         xlo
         xmid
         
        if (feval(f,xmid)>feval(f,xmid+delta))
          xhi = xmid + delta
          % Plot the current interval
            plot(xhi,feval(f,xhi),'gx','Markersize',10);
            
            finished = 1;
            
        else
          xlo  = xmid;
          xmid = xmid + delta;
          % Plot the current interval
            plot(xlo,feval(f,xlo),'rx','Markersize',10);
            plot(xmid,feval(f,xmid),'kx','Markersize',10);
            
        end
	
        k = k+1;
	
      end
    
  else

    xhi = xlo + delta;
    
    % Plot the current interval
    plot(xlo,feval(f,xlo),'rx','Markersize',10);
    plot(xhi,feval(f,xhi),'gx','Markersize',10);
    
    k = k+1;

    % Reduce
      finished = 0;
      
      while (finished==0)
        delta = 0.5*delta;

        % Display the values of the variables
          '----------'
          k
          delta
          xlo
          xhi

        if (feval(f,xlo+delta)>feval(f,xlo))
          xmid = xlo + delta
          % Plot the current interval
          plot(xmid,feval(f,xmid),'kx','Markersize',10);
          
	      finished = 1;
          
        else
          xhi  = xlo + delta;
          % Plot the current interval
          plot(xhi,feval(f,xhi),'gx','Markersize',10);
	
        end
	
        k = k+1;

      end
  end
  
  % Display the final values of the variables
    '----------'
    xvalues = [xlo,xmid,xhi]
    fvalues = [feval(f,xlo),feval(f,xmid),feval(f,xhi)]
    plot(xlo,feval(f,xlo),'bo','Markersize',10);
    plot(xmid,feval(f,xmid),'bo','Markersize',10);
    plot(xhi,feval(f,xhi),'bo','Markersize',10);

function [xlo,xmid,xhi] = nlp_oned_threepoint_max(f,xlo,delta)
   k = 0;
  '----------------------------'
   k
   delta
   xlo
 if (feval(f,xlo+delta)>feval(f,xlo))xmid = xlo + delta;

    plot(xlo,feval(f,xlo), 'rx' , 'Markersize' ,10);
    plot(xmid, feval(f,xmid), 'kx' , 'Markersize' , 10);
    k = k+1;
    finished = 0;

    while (finished==0)
      delta = 2*delta;
      '--------------------------'
      k
      delta
      xlo
      xmid
      if (feval(f,xmid)>feval(f,xmid+delta))
        xhi xmid + delta

        plot(xhi,feval(f,xhi), 'gx' , 'Markersize' ,10);
        finished = 1;
      else
        xlo= xmid;
        xmid = xmid +delta;

        plot(xlo,feval(f,xlo) , ' rx' , 'Markersize' ,10);
        plot(xmid,feval(f ,xmid), 'kx' , 'Markersize' , 10);
      end
      k = k+1;
    end
  else
    xhi = xlo +delta;
    plot(xlo,feval(f,xlo) , 'rx' , 'Markersize' ,10);
    plot(xhi,feval(f,xhi), 'gx ' , 'Markersize' ,10);
    k = k+1;
    finished = 0;
    while (finished==0)
      delta =0.5*delta;
      '------------------'
      k
      delta
      xlo
      xhi
    if (feval(f,xlo+delta)>feval(f,xlo))
      xmid =xlo + delta

      plot( xmid ,feval(f,xmid) , 'kx ' , 'Markersize',10);
      finished = 1;
      else
      xhi =xlo + delta;
      plot(xhi,feval(f,xhi) , 'gx ' , 'Markersize' ,10);
    end
    k = k+1;
  end
end
'---------------'
xvalues = [xlo, xmid ,xhi]
fvalues = [feval(f,xlo),feval(f,xmid),feval(f,xhi)]
plot(xlo,feval(f,xlo), 'bo ', 'Markersize',10);
plot(xmid,feval(f,xmid) , 'bo' , 'Markersize' , 10);
plot(xhi,feval(f,xhi) , 'bo' , 'Markersize' ,10);

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