fixed replace_zeros!

practicalfunctions.jl

@@ -434,7 +434,7 @@ function replace_zeros!(p::PolyElem{T}, d, dp = -1, k = -1) where T
     for i in 0:deg
         if T <: PolyElem
             set_coefficient!(p,i,replace_zeros!(coeff(p,i),d,dp,k))
-        else
+        elseif coeff(p,i) == 0
             set_coefficient!(p,i,d)
         end
     end