Let us say I want to show how the Taylor's series for Sin behaves:
In[94]:= Plot[Normal[Series[Sin[x], {x, 0, 3}]], {x, -π, π}]
During evaluation of In[94]:= General::ivar: -3.14146 is not a valid variable. >>
During evaluation of In[94]:= General::ivar: -3.14146 is not a valid variable. >>
During evaluation of In[94]:= General::ivar: -3.14146 is not a valid variable. >>
During evaluation of In[94]:= General::stop: Further output of General::ivar will be suppressed during this calculation. >>
However, if I just evaluate
In[95]:= Normal[Series[Sin[x], {x, 0, 3}]]
Out[95]= x - x^3/6
In[96]:= Plot[x - x^3/6, {x, -π, π}]
Out[96]=
It works fine. What is going on? I am doing this because I want to insert the plot in a Manipulate and then see how the functions behave with more terms of the series.
Update:
Using the answer, I can do
Plot[Evaluate@Normal[Series[Sin[x], {x, 0, 3}]], {x, -π, π}]
However, if I try to compare as in
Plot[{Sin[x], Evaluate@Normal[Series[Sin[x], {x, 0, 3}]]}, {x, -π, π}]
it doesn't work while the explicit
Plot[{Sin[x], x - x^3/6}, {x, -π, π}]
does.