Matlab画laplace变换后的图像的问题

clear,clc,close all;x=xlsread('H-N数据001(-90)',-1);y0=xlsread('H-N数据001(-90)',-1);figure;plot(x,y0);xlabel('采集通道');ylabel('data');y1=y0.^2;figure;plot(x,y1);y2=smooth(y1,5);figure;plot(x,y2);syms s t;f=poly2sym(y2,'s');ff=ilaplace(f);y3=abs(ff);figure;surf(t,f,y3);  colormap(hsv);
Invalid input argumentsError in ==> surf at 81    hh = double(graph3d.surfaceplot(args{:},'parent',cax));    Error in ==> laplace at 24surf(t,f,y3);  刚刚开始学matlab，不知道该怎么解决这个问题，请帮忙改一下程序，谢谢！