SED navigation bar go to SED home page go to Dataplot home page go to NIST home page SED Home Page SED Staff SED Projects SED Products and Publications Search SED Pages
Dataplot Vol 2 Vol 1

IWECDF

Name:
    IWECDF (LET)
Type:
    Library Function
Purpose:
    Compute the standard form of the inverted Weibull cumulative distribution function with tail length parameter gamma.
Description:
    The standard form of the inverted Weibull cumulative distribution function is:

      F(x) =EXP{-(x)**(-gamma)}      x, gamma > 0
Syntax:
    LET <y2> = IWECDF(<y1>,<GAMMA>)             <SUBSET/EXCEPT/FOR qualification>
    where <y1> is a variable, number, or parameter;
                <y2> is a variable or a parameter (depending on what <y1> is) where the computed inverted Weibull cdf value is stored;
                <GAMMA> is a positive number or parameter that specifies the tail length parameter;
    and where the <SUBSET/EXCEPT/FOR qualification> is optional.
Examples:
    LET A = IWECDF(3,2)
    LET A = IWECDF(A1,4)
    LET X2 = IWECDF(X1,8)
Note:
    The general form of the inverted Weibull cumulative distribution function is:

      F(x) =EXP{-[(x-u)/beta]**(-gamma)}   x > mu; gamma, betas > 0
    where mu is the location parameter and beta is the scale parameter.
Default:
    None
Synonyms:
    None
Related Commands:
    IWEPDF = Compute the inverted Weibull probability density function.
    IWEPPF = Compute the inverted Weibull percent point function.
    WEIPDF = Compute the Weibull probability density function.
    GAMPDF = Compute the gamma probability density function.
    CHSPDF = Compute the chi-square probability density function.
    NORPDF = Compute the normal probability density function.
    LOGPDF = Compute the lognormal probability density function.
    PPCC PLOT = Generate a PPCC plot.
    PROBABILTY PLOT = Generate a probability plot.
    RANDOM NUMBERS = Generate random numbers.
Reference:
    "Continuous Univariate Distributions: Volume 1", 2nd. Ed., Johnson, Kotz, and Balakrishnan, 1994, John Wiley, pp. 693.
Applications:
    Reliability Analysis
Implementation Date:
    2001/10
Program:
        MULTIPOT 2 2 
        MULTIPLOT CORNER COORDINATES 5 5 95 95 
        MULTIPLOT SCALE FACTOR 2 
        LABEL CASE ASIS
        Y1LABEL Probability 
        Y1LABEL DISPLACEMENT 12 
        X1LABEL X 
        TITLE IWECDF (GAMMA = 0.5) 
        PLOT IWECDF(X,0.5) FOR X = 0.01 0.01 5 
        TITLE IWECDF (GAMMA = 1) 
        PLOT IWECDF(X,1) FOR X = 0.01 0.01 5 
        TITLE IWECDF (GAMMA = 2) 
        PLOT IWECDF(X,2) FOR X = 0.01 0.01 5 
        TITLE IWECDF (GAMMA = 5) 
        PLOT IWECDF(X,5) FOR X = 0.01 0.01 5 
        END OF MULTIPLOT 
        
    plot generated by sample program

Date created: 10/9/2001
Last updated: 4/4/2003
Please email comments on this WWW page to alan.heckert@nist.gov.