Matlab interpgui

function interpgui(arg1,arg2)%INTERPGUI  Behavior of interpolating functions.%   Demonstrates interpolation by a piecewise linear interpolant,%   a polynomial, a spline, and a shape preserving Hermite cubic.%   INTERPGUI(x,y) starts with a plot of y vs. x.%   INTERPGUI(y) starts with equally spaced x's.%   INTERPGUI(n) starts with y = zeros(1,n).%   INTERPGUI with no arguments starts with eight zeros.%   The interpolation points can be varied with the mouse.%   If x is specified, it remains fixed.%%   See also SPLINETX, PCHIPTX, POLYINTERP, PIECELIN.if nargin == 0 | isnumeric(arg1)   % Interpret arguments   if nargin == 0      % interpgui with no arguments      n = 8;      x = 1:n;      y = zeros(1,n);   elseif length(arg1) == 1      % interpgui(n)      n = arg1;      x = 1:n;      y = zeros(1,n);   elseif nargin == 1      % interpgui(y)      n = length(arg1);      x = 1:n;      y = arg1(:)';   elseif length(arg1) == length(arg2)      % interpgui(x,y)      [x,k] = sort(arg1(:)');      y = arg2(k)';   else      error('Two arguments must have same length')   end   arg1 = [];   % Initialize figure   shg   clf reset   set(gcf,'doublebuffer','on', ...     'name','Interp gui', 'numbertitle','off', ...     'windowbuttondown',['interpgui(''move''); set(gcf,' ...        '''windowbuttonmotion'',''interpgui(''''move'''')'')'], ...     'windowbuttonup','set(gcf,''windowbuttonmotion'','''')');   % Initialize plots   n = length(x);   h = diff(x);   u = zeros(1,128*(n+1));   j = 1:128;   s = (1+sin((j-65)/128*pi))/2;   u(j) = x(1)+(s-1)*h(1);   for k = 1:n-1      u(128*k+j) = x(k)+s*h(k);   end   u(128*n+j) = x(n)+s*h(n-1);   p = plot(x,y,'o',u,zeros(4,length(u)),'-');   ymin = min(y);   ymax = max(y);   ydel = ymax-ymin;   if ydel == 0; ydel = 1; end   axis([min(u) max(u) ymin-0.5*ydel ymax+0.5*ydel])   title('Interpolation')   % Controls   uicontrol('units','normal','pos',[.68 .13 .12 .18], ...     'style','frame','background','white')   F = {'linear','poly','spline','pchip'};   pos = [.69 .26 .09 .04];   vis = 0;   for k = 1:4      uicontrol('units','normal','pos',pos, ...         'style','check','string',F{k},'value',vis, ...         'background','white','foreground',get(p(k+1),'color'), ...         'callback','interpgui(''cb'')');      pos(2) = pos(2)-.04;   end   uicontrol('units','normal','pos',[.85 .01 .10 .06], ...      'style','push','string','close','tag','reset/close', ...      'callback','close(gcf)');   % Remember original data   xfree = (nargin < 2);   set(gcf,'userdata',xfree)   set(gca,'userdata',{x,y})endp = flipud(get(gca,'children'));x = get(p(1),'xdata');y = get(p(1),'ydata');n = length(x);h = diff(x);u = zeros(1,128*(n+1));j = 1:128;s = (1+sin((j-65)/128*pi))/2;u(j) = x(1)+(s-1)*h(1);for k = 1:n-1   u(128*k+j) = x(k)+s*h(k);endu(128*n+j) = x(n)+s*h(n-1);if isequal(arg1,'reset')   % Restore original data   xy = get(gca,'userdata');   x = xy{1};   y = xy{2};   set(findobj('tag','reset/close'),'string','close', ...      'callback','close(gcf)');elseif isequal(arg1,'move')   % Respond to mouse motion   z = get(gca,'currentpoint');   z = z(1,:);   p = flipud(get(gca,'children'));   e = abs(x-z(1));   k = min(find(e == min(e)));   xfree = get(gcf,'userdata');   if xfree      x(k) = z(1);   end   y(k) = z(2);   set(findobj('tag','reset/close'),'string','reset', ...      'callback','interpgui(''reset'')');endax = axis;set(p(1),'xdata',x,'ydata',y)set(p(2),'xdata',u,'ydata',piecelin(x,y,u));set(p(3),'xdata',u,'ydata',polyinterp(x,y,u));set(p(4),'xdata',u,'ydata',splinetx(x,y,u));set(p(5),'xdata',u,'ydata',pchiptx(x,y,u));axis(ax);% Visibilityb = flipud(get(gcf,'children'));onf = {'off','on'};for k = 1:4   % Interpolants   set(p(k+1),'visible',onf{get(b(k+2),'value')+1})end