% mm4decho onx=-7.5:.5:7.5;          % create a data set - the famous sombreroy=x;[X Y]=meshgrid(x,y);      % create plaid dataR=sqrt(X.^2+Y.^2)+eps;Z=sin(R)./R;figure(1)colormap(hot)surf(X,Y,Z,Z)             % default color ordertitle('Default color')% press any key to continuepausesurf(X,Y,Z,-Z)            % plot and reverse the default color ordertitle('Flip color upside-down')% press any key to continuepausesurf(X,Y,Z,X)             % color varies along the X axistitle('Vary color along X-axis')% press any key to continuepausesurf(X,Y,Z,X+Y)           % color varies along the XY diagonaltitle('Vary color along X-Y diagonal')% press any key to continuepausesurf(X,Y,Z,R)   	      % color varies radially from the centertitle('Vary color radially in x-y plane')% press any key to continuepausesurf(X,Y,Z,abs(del2(Z)))  % color varies with absolute value of Laplaciantitle('Vary color by Laplacian')% press any key to continuepause[dZdx,dZdy]=gradient(Z);surf(X,Y,Z,abs(dZdx))     % color varies with absolute slope in x-directiontitle('Vary color with absolute slope in X-direction')% press any key to continuepausesurf(X,Y,Z,abs(dZdy))     % color varies with absolute slope in y-directiontitle('Vary color with absolute slope in Y-direction')% press any key to continuepausedZ=sqrt(dZdx.^2 + dZdy.^2);surf(X,Y,Z,dZ)            % color varies with magnitude of slopetitle('Vary color with magnitude of slope')echo off