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Dataplot Vol 1 Auxiliary Chapter

SLAPDF

Name:
    SLAPDF (LET)
Type:
    Library Function
Purpose:
    Compute the slash probability density function.
Description:
    The slash distribution has the following probability density function:

      f(x) = (NORPDF(0) - NORPDF(X))/(X**2)  X <> 0
= 0.5*NORPDF(0)  X = 0

    with NORPDF denoting the probability density function of the standard normal distribution.

    The most common use of the slash distribution is in simulation studies. It is a useful distribution in this context because it has heavier tails than a normal distribution, but it is not as pathological as the Cauchy distribution.

Syntax:
    LET <y> = SLAPDF(<x>)             <SUBSET/EXCEPT/FOR qualification>
    where <x> is a variable, a number, or a parameter;
                <y> is a variable or a parameter (depending on what <x> is) where the computed slash pdf value is stored;
    and where the <SUBSET/EXCEPT/FOR qualification> is optional.
Examples:
    LET A = SLAPDF(3)
    LET X2 = SLAPDF(X1)
Note:
    You can generate random numbers from a slash distribution with the following command:

      LET Y = SLASH RANDOM NUMBERS FOR I = 1 1 N
Default:
    None
Synonyms:
    None
Related Commands:
    SLACDF = Compute the slash cumulative distribution function.
    SLAPPF = Compute the slash percent point function.
    NORPDF = Compute the normal probability density function.
    LOGPDF = Compute the logistic probability density function.
    CAUPDF = Compute the Cauchy probability density function.
    RANDOM NUMBERS = Generate random numbers from 60+ univariate distributions.
Reference:
    "Continuous Univariate Distributions: Volume 1", 2nd. Ed., Johnson, Kotz, and Balakrishnan, John Wiley, 1994, (page 63).
Applications:
    Simulation
Implementation Date:
    2003/3
Program:
     
    TITLE SLASH PDF
    PLOT SLAPDF(X)  FOR X = -10 0.01 10
        
    plot generated by sample program

Date created: 2/3/2004
Last updated: 2/3/2004
Please email comments on this WWW page to alan.heckert@nist.gov.