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I am pretty sure I have made an obvious mistake. I want to plot a Taylor polynomial of a degree 4 around the point (0, 0). So I have defined a function

f[x_, y_] := Cos[x + y]

Then I write a Taylor series up to 4th degree

Series[f[x, y], {x, 0, 4}, {y, 0, 4}]

I can plot the function f, but when I try to plot series I get errors. I believe it is because. when computing the series, along from the terms I will also get a remainder, which can not be plotted.

Any help would be much appreciated.

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    – rhermans
    Commented May 15, 2017 at 12:34
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    – rhermans
    Commented May 15, 2017 at 12:34

1 Answer 1

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Use Normal and Evaluate,e.g.:

t[n_] := Plot3D[
  Evaluate[Series[Cos[x + y], {x, 0, n}, {y, 0, n}] // Normal], {x, 0,
    2 Pi}, {y, 0, 2 Pi}]

An animation of truncated series: 1 to 20:

enter image description here

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