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Quotient difference

Mathematical concept
The difference quotient is the mean difference, and the first order difference quotient is the approximate value of the first derivative. reciprocity step (h) Of Discrete function F (x), its n-order difference quotient is the ratio of its n-order difference to the n-power of its step size. For example, when n=1, if the difference is forward or backward, the first order difference quotient obtained is the first order approximation of the derivative of the function; If the difference is centered, the first order difference quotient obtained is the second order approximation of the derivative. [1]
Chinese name
Quotient difference
Foreign name
difference quotient
Discipline
mathematics
Related concepts
Interpolation, interpolation node, difference quotient table, etc
Type
Mathematical concept

definition

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Given function
and interpolation node
use
express
About nodes
K-th Difference Quotient (k=1, 2,..., n), which can be defined recursively as
among
About nodes
0 order difference quotient of is defined as its function value, that is
[2]

Difference quotient table

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The difference quotient table (Table 1) can be constructed and calculated recursively by column
Difference quotient of each order of: [2]
Table 1 Calculation of Difference Quotient
node
Difference quotient of order 0
First order difference quotient
Second order difference quotient
3rd order difference quotient
Fourth order difference quotient
The specific calculation process is
Order 0 difference quotient:
First order difference quotient:
Second order difference quotient:
Third order difference quotient:

Nature of difference quotient

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According to the definition of difference quotient Mathematical induction It can be proved that the difference quotient has the following properties:

Nature 1

yes
yes
as

Nature 2

(Symmetry) Quotient difference
It is independent of the order of interpolation nodes, that is
among
yes
Any of array [2]