function fy=tsquare(fx) 
%  tlinear(fx)  Generates a probability function fy where Y=g(X), g(X)=X^2, 
%               and X has probability function fx.  May require use of the 
%               smooth function. 
if ispf(fx)==0 
   error('not a valid probability function') 
end 
x=xvals(fx); 
p=pvals(fx); 
L=length(x); 
ax=abs(x); 
ylow=(min(ax))^2; 
yhigh=(max(ax))^2; 
Fx=getcf(fx); 
if isdiscrt(fx)==1 
   y=[ylow:yhigh]; 
else 
   y=[ylow:(yhigh-ylow)/L:yhigh]; 
end 
P=pval(Fx, sqrt(y))-pval(Fx, -sqrt(y)); 
if ylow==0 
   P(1)=pval(Fx, 0); 
end 
Fy=[Fx(1,:); y' P']; 
if iscf(Fy)==0 
   error('failed') 
end 
fy=getpf(Fy); 
if isdiscrt(fx)==1 
   y=xvals(fy); 
   p=pvals(fy); 
   y=y(find(p>0)); 
   p=p(find(p>0)); 
   fy=[fy(1,:); y' p']; 
end