Difference between revisions of "SigmaXX Command"

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;SigmaXX[ <List of Points> ]
 
;SigmaXX[ <List of Points> ]
 
:Calculates the sum of squares of the ''x''-coordinates of the given points.
 
:Calculates the sum of squares of the ''x''-coordinates of the given points.
:{{Example|1=Let <code><nowiki>list = { (-3, 4), (-1, 4), (-2, 3), (1, 3), (2, 2), (1, 5) }</nowiki></code> be a list of points. <code><nowiki>SigmaXX[ Liste ]</nowiki></code> yields ''a = 20''.}}
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:{{Example|1=Let <code><nowiki>list1 = { (-3, 4), (-1, 4), (-2, 3), (1, 3), (2, 2), (1, 5) }</nowiki></code> be a list of points. <code><nowiki>SigmaXX[ list1 ]</nowiki></code> yields the value ''20''.}}
  
  
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; SigmaXX[ <List of Numbers>, <List of Frequencies> ]
 
; SigmaXX[ <List of Numbers>, <List of Frequencies> ]
 
:Calculates the weighted sum of squares of the given numbers.
 
:Calculates the weighted sum of squares of the given numbers.
:{{Example|1= Let <code><nowiki>list = {3, 2, 4, 3, 3, 2, 1, 1, 2, 3, 3, 4, 5, 3, 2, 1, 1, 2, 3}</nowiki></code> be a list of numbers. <code><nowiki>Unique[ list1 ]</nowiki></code> yields ''list2 = {1, 2, 3, 4, 5}'' and <code><nowiki>Frequency[ list1 ]</nowiki></code> yields ''list3 = {4, 5, 7, 2, 1}''. Command <code><nowiki>SigmaXX[ list2, list3 ]</nowiki></code> yields ''a = 144''.}}
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:{{Example|1= Let <code><nowiki>list1 = {3, 2, 4, 3, 3, 2, 1, 1, 2, 3, 3, 4, 5, 3, 2, 1, 1, 2, 3}</nowiki></code> be a list of numbers. <code><nowiki>Unique[ list1 ]</nowiki></code> yields ''list2 = {1, 2, 3, 4, 5}'' and <code><nowiki>Frequency[ list1 ]</nowiki></code> yields ''list3 = {4, 5, 7, 2, 1}''. Command <code><nowiki>SigmaXX[ list2, list3 ]</nowiki></code> yields the value ''144''.}}

Revision as of 10:44, 4 April 2015




SigmaXX[ <List of Points> ]
Calculates the sum of squares of the x-coordinates of the given points.
Example: Let list1 = { (-3, 4), (-1, 4), (-2, 3), (1, 3), (2, 2), (1, 5) } be a list of points. SigmaXX[ list1 ] yields the value 20.


SigmaXX[ <List of Raw Data> ]
Calculates the sum of squares of the given numbers.
Example: In order to work out the variance of a list you may use SigmaXX[list] / Length[list] - Mean[list]^2.


SigmaXX[ <List of Numbers>, <List of Frequencies> ]
Calculates the weighted sum of squares of the given numbers.
Example: Let list1 = {3, 2, 4, 3, 3, 2, 1, 1, 2, 3, 3, 4, 5, 3, 2, 1, 1, 2, 3} be a list of numbers. Unique[ list1 ] yields list2 = {1, 2, 3, 4, 5} and Frequency[ list1 ] yields list3 = {4, 5, 7, 2, 1}. Command SigmaXX[ list2, list3 ] yields the value 144.
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