function interpgui(arg1,arg2,arg3) %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. % % Added July, 2012: With three arguments, INTERPGUI(x,y,v) initializes % the check boxes to v, a scalar or vector with elements from 1:4. % % 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(:)'; y = y(k); else error('Two arguments must have same length') end arg1 = []; % Initialize figure shg clf reset set(gcf,'doublebuffer','on', ... '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(5,length(u)),'-'); set(p(6),'color',[.25 .25 .25]) 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 .69 .14 .22], ... 'style','frame','background','white') F = {'linear','poly','spline','pchip','v5cubic'}; pos = [.69 .86 .12 .04]; vis = 0; for k = 1:5 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}) end p = 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); end u(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'')'); end ax = 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)); set(p(6),'xdata',u,'ydata',interp1(x,y,u,'v5cubic')); axis(ax); % Visibility b = flipud(get(gcf,'children')); % Added July, 2012: if nargin == 3 set(b(arg3+2),'value',1) end % onf = {'off','on'}; for k = 1:4 % Interpolants set(p(k+1),'visible',onf{get(b(k+2),'value')+1}) end