RootSum
 Usage
• RootSum[f, form] 表示对所有满足多项式方程 f[x]  0 的 x 求 form[x]的和.
Notes
• f 必须是诸如(#^5 - 2 # + 1)&的一个Function对象. • form 不必是一个多项式函数. • Normal[expr]把RootSum对象展开为包含 Root对象的显式和. • f 和 form 可以包含符号参数. • 只要form是一个有理函数,RootSum[f, form]将自动进行化简. • RootSum 常在计算有理函数的积分时生成.
 Further Examples
This gives the sum of the seventh powers of the roots of the quintic.
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Here is the sum of the logarithms.
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The sum of exponentials is not evaluated explicitly, but we can get its numerical value with N.
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In this polynomial the coefficients of the linear term is symbolic. We can get numerical results by substitution.
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