sdevn

The sdevn function returns the standard deviation of a general lua table that may contain a multi-dimensional array or a mixture of numbers, strings, named keys, and sub-tables. Only numeric values found in the table are used in the calculation. The related sdev function calculates the mean of a 1-dimensional array, CImage, or list of numbers. Since an array is a specific type of table that contains only numbers or sub-tables, this function can also be used for arrays.

Syntax

nStdDev = sdevn( tbl )

bullet.gif    tbl is a general lua table.

bullet.gif    nStdDev is the standard deviation of the values.

Examples

The following script returns the standard deviation of a table containing 1 million random numbers.

t = random( 1000000 )

-- create a table of numbers

sd = sdevn( t )

-- find the standard deviation

Printf("Sdev= %lg\n", sd )

-- list the result

  

The next example computes the standard deviation of an ugly, complex table:

t = { 6, -2, 15, "a", {5,"b"}, c="5.4" }

 

sd = sdevn(t)

-- find the standard deviation

Printf("Sdev = %lg\n", sd )

-- result: Sdev = 6.97615 using 4 values

Related Topics

Table and Array Functions, sdevxn, meansdevn, sdev


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