# Converting Power Series to Normal Expressions

Normal[expr] | convert a power series to a normal expression |

Converting power series to normal expressions.

Power series in *Mathematica* are represented in a special internal form, which keeps track of such attributes as their expansion order.

For some purposes, you may want to convert power series to normal expressions. From a mathematical point of view, this corresponds to truncating the power series, and assuming that all higher-order terms are zero.

This generates a power series, with four terms.

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Squaring the power series gives you another power series, with the appropriate number of terms.

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Normal truncates the power series, giving a normal expression.

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You can now apply standard algebraic operations.

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SeriesCoefficient[series,n] | give the coefficient of the n order term in a power series |

Extracting coefficients of terms in power series.

This gives the coefficient of

in the original power series.

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This gives the coefficient for the term

in the Taylor expansion of the function

about zero.

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