Plus


表示项的和.

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  • Plus 有属性 FlatOrderlessOneIdentity.
  • 如同用在模式 中的一样,Plus 的自变量的默认值是 . »
  • Plus[] 取为 .
  • Plus[x]x.
  • x+0 计算 x,但 x+0.0 不会改变.
  • 在类似 的混合分式中,隐含的加法可以输入为 Esc+Esc \[ImplicitPlus]. 这样计算,但隐含的加法是一个优先级高于 的运算符.
  • 与其它函数不同,Plus 在用户定义规则前应用内置规则. 因此,如同 的定义是不可能的.

背景
背景

  • Plus is a function that does addition (summation) of expressions. The expression Plus[a,b,c,] is commonly represented using the shorthand syntax . Special cases include Plus[], which is taken to be 0, and Plus[x], which is taken to be x.
  • Plus sorts its arguments and collapses any terms of the same type. Plus also threads element-wise over lists.
  • To perform summation at a particular level of a list or to apply compensative summation to reduce numerical error for inexact summands, the function Total can be used. Accumulate gives a list of the successive accumulated totals of elements in a list. AddTo, Increment, and PreIncrement can be used to increase the value of a given variable. Minus gives the arithmetic negation of an expression, and Subtract gives the difference of two numbers.
  • Summation of a function over a range or list of arguments is done using the function Sum.
1988年引入
(1.0)
| 2007年更新
(6.0)