DiscreteRatio[f,i]
给出离散率
.
DiscreteRatio[f,{i,n}]
给出多重离散率.
DiscreteRatio[f,{i,n,h}]
给出步长为 h 的多重离散率.
DiscreteRatio[f,i,j,…]
计算关于 i、j、… 的偏差分率.
DiscreteRatio
DiscreteRatio[f,i]
给出离散率
.
DiscreteRatio[f,{i,n}]
给出多重离散率.
DiscreteRatio[f,{i,n,h}]
给出步长为 h 的多重离散率.
DiscreteRatio[f,i,j,…]
计算关于 i、j、… 的偏差分率.
更多信息和选项
- DiscreteRatio[f,i] 可以输入为 if. 字符 可以通过输入
dratio
或 \[DiscreteRatio]得到. 变量 i 作为下标输入. - 所有没有明确依赖于给定变量的数据量的离散率等于一.
- 多重离散率由较低的离散率递归定义.
- 离散率是无穷积的逆运算. »
- DiscreteRatio[f,…,Assumptions->assum] 在计算离散率中采用假设 assum.
范例
打开所有单元 关闭所有单元基本范例 (4)
DiscreteRatio[f[i], i]DiscreteRatio[r ^ i, i]Subscript[, i]Pochhammer[x, i]离散率是 Product 的逆运算:
Subscript[∏, i]Subscript[, i]f[i]Subscript[, i]Subscript[∏, i]f[i]范围 (20)
基本用法 (4)
DiscreteRatio[f[i], i]DiscreteRatio[f[i], {i, 2}]DiscreteRatio[f[i]f[i + 1]f[i + 2], i]DiscreteRatio[(f[i]f[i + 1]f[i + 2]/g[i]g[i + 1]), i]DiscreteRatio[f[i], {i, 1, h}]DiscreteRatio[f[i], {i, 2, h}]DiscreteRatio[f[i, j], i, j]DiscreteRatio[f[i, j], i, {j, 2}]DiscreteRatio[f[i, j], i, {j, 2, 1 / 3}]特殊序列 (14)
Subscript[, x]x^2Subscript[, x]((x - Subscript[r, 1])(x - Subscript[r, 2]))Subscript[, x](1 + x/1 + x^2)Subscript[, x](((x - Subscript[r, 1])(x - Subscript[r, 2])/(x - Subscript[p, 1])(x - Subscript[p, 2])))阶乘函数具有包括 FactorialPower 在内的有理比值:
FactorialPower[x, 5]//FunctionExpandDiscreteRatio[%, x]DiscreteRatio[FactorialPower[a, x], x]Pochhammer[x, 5]DiscreteRatio[%, x]DiscreteRatio[Pochhammer[a, x], x]DiscreteRatio[Factorial[x], x]DiscreteRatio[Gamma[x], x]DiscreteRatio[Binomial[x, k], x]DiscreteRatio[Binomial[n, x], x]DiscreteRatio[r^x, x]指数序列的比对应于指数的 DifferenceDelta:
Subscript[, x]r^f[x]r^Subscript[, x]f[x]DiscreteRatio[(FactorialPower[x, Subscript[a, 1]]Binomial[x, Subscript[a, 2]]/Pochhammer[x, Subscript[b, 1]]Factorial[x])r^x, x]超几何项具有有理比值,因此 CatalanNumber 是一个超几何项:
DiscreteRatio[CatalanNumber[x], x]FunctionExpand[CatalanNumber[x]]DiscreteRatio[a q ^ x + b q ^ (2x), x]DiscreteRatio[(q^x - Subscript[r, 1])(q^x - Subscript[r, 2]), x]DiscreteRatio[(a q ^ x + b q ^ (2x)/1 + q^x), x]DiscreteRatio[((q^x - Subscript[r, 1])(q^x - Subscript[r, 2])/(q^x - Subscript[p, 1])(q^x - Subscript[p, 2])), x]q 阶乘函数具有包括 QPochhammer 在内的 q 有理比值:
QPochhammer[x, q, 5]//FunctionExpandDiscreteRatio[%, x]DiscreteRatio[QPochhammer[a, q, x], x]DiscreteRatio[QFactorial[x, q], x]DiscreteRatio[QBinomial[n, x, q], x]DiscreteRatio[QBinomial[x, k, q], x]DiscreteRatio[(QBinomial[a, x, q]QFactorial[x, q]/QPochhammer[b, q, x]), x]阶乘函数的乘积具有阶乘比值,包括 BarnesG:
DiscreteRatio[BarnesG[x], x]DiscreteRatio[%, x]Hyperfactorial 是 ii 的乘积:
DiscreteRatio[Hyperfactorial[x], x]{DiscreteRatio[Binomial[n, k], n], DiscreteRatio[Binomial[n, k], k]}f = Refine[PDF[BinomialDistribution[n, p], k], 0 ≤ k < n]{DiscreteRatio[f, n], DiscreteRatio[f, k]}GammaRegularized 关于
的差分是超几何项:
DifferenceDelta[GammaRegularized[n, z], n]1 + % / GammaRegularized[n, z]DiscreteRatio[GammaRegularized[n, z], n]BetaRegularized 情况相似:
DiscreteRatio[BetaRegularized[z, n, m], m]DifferenceDelta[MarcumQ[n, a, z], n]特殊运算符 (2)
DiscreteRatio 是 Product 的逆运算:
DiscreteRatio[Product[f[i], i], i]Product[DiscreteRatio[f[i], i], i]DiscreteRatio[Product[f[k], {k, i + m, i + p}], i]DiscreteRatio[Product[f[i, j], i, j], i, j]DiscreteRatio[Limit[f[x], x -> a], a]DiscreteRatio[Integrate[f[x], x], x]DiscreteRatio[Sum[f[k], k], k]DiscreteRatio[Integrate[f[x], {x, a, b}], x]DiscreteRatio[Limit[f[x], x -> a], x]应用 (6)
一个几何序列的定义属性是它的 DiscreteRatio 是常量:
DiscreteRatio[c^a k + b, k]RSolve[y[k + 1] == (1 + r) y[k], y[k], k]DiscreteRatio 给出复合序列的复利:
DiscreteRatio[y[k] /. First[%], k]DiscreteRatio[(2^(1/(12)))^i440 , i]f = Piecewise@Table[{(2^(1/(12)))^i440 2Pi t, i ≤ t < i + 1}, {i, 0, 11}];Play[Sin[f], {t, 0, 12}]Sound[Table[SoundNote[i], {i, 0, 11}]]a[i_] := E ^ (-i)(3i + 1)! / (4i)!计算这个序列的 DiscreteRatio:
rat = DiscreteRatio[a[i], i]Limit[rat, i -> ∞]用 SumConvergence 验证这个结果:
SumConvergence[a[i], i]Product[(i + 1) / (2i + 5), i]一个乘积的 DiscreteRatio 等价于因子:
DiscreteRatio[%, i]用一个更高的步长位移率从 RSolve 中验证解:
RSolve[{y[k + 2] == ((k + 1)y[k]) / (k + 2), y[0] == 1, y[1] == 2}, y, k]DiscreteRatio[y[k] /. %[[1]], {k, 1, 2}]//FullSimplify属性和关系 (6)
DiscreteRatio 是不定 Product 的逆:
DiscreteRatio[Product[f[k], k], k]Product[DiscreteRatio[f[k], k], k]DiscreteRatio 在积和整数幂上的分配:
{DiscreteRatio[f[k] g[k], k], DiscreteRatio[f[k] g[k], k]}{DiscreteRatio[f[k]^3, k], DiscreteRatio[f[k], k]^3}DiscreteRatio 与 DifferenceDelta 紧密相关:
{Log[DiscreteRatio[f[k], k]], DifferenceDelta[Log[f[k]], k]}{DiscreteRatio[Exp[f[k]], k], Exp[DifferenceDelta[f[k], k]]}DiscreteRatio 可以 DifferenceDelta 的形式表示:
r[n] = DiscreteRatio[y[n], n];
d[n] = DifferenceDelta[y[n], n];r[n] == 1 + d[n] / y[n]//Simplify使用 Ratios 计算相邻两项的比值:
Ratios[Table[f[k], {k, 4}]]Table[Evaluate@DiscreteRatio[f[k], k], {k, 3}]Ratios[Table[f[k], {k, 4}], 2]Table[Evaluate@DiscreteRatio[f[k], {k, 2}], {k, 2}]Ratios[Table[f[k], {k, 4}], 1, 2]Table[Evaluate@DiscreteRatio[f[k], {k, 1, 2}], {k, 2}]使用 PowerRange 生成具有恒定比值的列表:
PowerRange[1, 8, 2]Ratios[%]DiscreteRatio[2 ^ k, k]巧妙范例 (1)
相关指南
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▪
- 离散微积分
文本
Wolfram Research (2008),DiscreteRatio,Wolfram 语言函数,https://reference.wolfram.com/language/ref/DiscreteRatio.html.
CMS
Wolfram 语言. 2008. "DiscreteRatio." Wolfram 语言与系统参考资料中心. Wolfram Research. https://reference.wolfram.com/language/ref/DiscreteRatio.html.
APA
Wolfram 语言. (2008). DiscreteRatio. Wolfram 语言与系统参考资料中心. 追溯自 https://reference.wolfram.com/language/ref/DiscreteRatio.html 年
BibTeX
@misc{reference.wolfram_2026_discreteratio, author="Wolfram Research", title="{DiscreteRatio}", year="2008", howpublished="\url{https://reference.wolfram.com/language/ref/DiscreteRatio.html}", note=[Accessed: 05-September-2026]}
BibLaTeX
@online{reference.wolfram_2026_discreteratio, organization={Wolfram Research}, title={DiscreteRatio}, year={2008}, url={https://reference.wolfram.com/language/ref/DiscreteRatio.html}, note=[Accessed: 05-September-2026]}