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Re: PolynomialQ ?

On Tuesday, June 11, 2002, at 05:00 AM, Juan wrote:

> Hi,I tried to check is a polynomial have a variable, ussing the function
> PolynomialQ.
> In[1]:=p = x^3 - 2*x^2 + x - 1;
> In[2]:=PolynomialQ[p, x]
> Out[2]=True
> In[3]:=PolynomialQ[p, y]
> Out[3]=True
> In[4]:=PolynomialQ[p, z^2]
> Out[4]=True
> In[5]:=PolynomialQ[p, {u, v}]
> Out[5]=True
> What is the thing I am doing wrong?
Nothing, p is a polynomial in all the variables you tried since it could 
always be the constant term in a zero degree polynomial.  If you want to 
know if an expression is a nonconstant polynomial in a variable, first 
check if the expression contains your variable, then check if it's a 
polynomial: If[FreeQ[expr,var],False,PolynomialQ[expr,var]].  You could 
also check if your variable is one of the independent variables of the 
polynomial: PolynomialQ[expr,var] && MemberQ[Variables[expr],var].



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