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Long Term Support Release

  • Bug fixes for general core bugs in 4.1.x will end 13 November 2023 (12 months).
  • Bug fixes for security issues in 4.1.x will end 10 November 2025 (36 months).
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Differences Between: [Versions 400 and 401] [Versions 401 and 402] [Versions 401 and 403]

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Defines 1 class

StandardNormal:: (5 methods):
  cumulative()
  distribution()
  inverse()
  gauss()
  zTest()


Class: StandardNormal  - X-Ref

cumulative($value)   X-Ref
NORMSDIST.

Returns the standard normal cumulative distribution function. The distribution has
a mean of 0 (zero) and a standard deviation of one. Use this function in place of a
table of standard normal curve areas.

NOTE: We don't need to check for arrays to array-enable this function, because that is already
handled by the logic in Normal::distribution()
All we need to do is pass the value through as scalar or as array.

param: mixed $value Float value for which we want the probability
return: array|float|string The result, or a string containing an error

distribution($value, $cumulative)   X-Ref
NORM.S.DIST.

Returns the standard normal cumulative distribution function. The distribution has
a mean of 0 (zero) and a standard deviation of one. Use this function in place of a
table of standard normal curve areas.

NOTE: We don't need to check for arrays to array-enable this function, because that is already
handled by the logic in Normal::distribution()
All we need to do is pass the value and cumulative through as scalar or as array.

param: mixed $value Float value for which we want the probability
param: mixed $cumulative Boolean value indicating if we want the cdf (true) or the pdf (false)
return: array|float|string The result, or a string containing an error

inverse($value)   X-Ref
NORMSINV.

Returns the inverse of the standard normal cumulative distribution

param: mixed $value float probability for which we want the value
return: array|float|string The result, or a string containing an error

gauss($value)   X-Ref
GAUSS.

Calculates the probability that a member of a standard normal population will fall between
the mean and z standard deviations from the mean.

param: mixed $value
return: array|float|string The result, or a string containing an error

zTest($dataSet, $m0, $sigma = null)   X-Ref
ZTEST.

Returns the one-tailed P-value of a z-test.

For a given hypothesized population mean, x, Z.TEST returns the probability that the sample mean would be
greater than the average of observations in the data set (array) — that is, the observed sample mean.

param: mixed $dataSet The dataset should be an array of float values for the observations
param: mixed $m0 Alpha Parameter
param: mixed $sigma A null or float value for the Beta (Standard Deviation) Parameter;
return: array|float|string (string if result is an error)