Skip to main content
MedCalc
Mail a PDF copy of this page to:
(Your email address will not be added to a mailing list)
working
Show menu

Weibull distribution functions

PDFWeibull(x,alpha,beta)

PDFWeibull(x,alpha,beta) returns the probability density at the value x of the Weibull distribution with shape parameter alpha and scale parameter beta.

This equals Excel's function Weibull.DIST(x,alpha,beta,FALSE).

The equation for the Weibull probability density function is:

$$f(x;\alpha,\beta) = \frac{\alpha}{\beta^\alpha} x^{\alpha-1} \mathrm{e}^{-(x/\beta)^{\alpha}} $$

The following graph shows the PDFWeibull distribution function for different values of the shape parameter alpha with scale parameter beta=1

Weibull probability density function for different values of alpha.

Calculator

PDFWeibull(,,)

Graph

PDFWeibull function
Function: PDFWeibull(,,)
  X-axis Y-axis
Minimum:
Maximum:
 

CDFWeibull(x,alpha,beta)

CDFWeibull(x,alpha,beta) returns the value at x of the cumulative Weibull distribution with parameters alpha and beta.

This equals Excel's function Weibull.DIST(x,alpha,beta,TRUE).

The equation for the Weibull cumulative distribution function is:

$$ F(x;\alpha,\beta) = 1- \mathrm{e}^{-(x/\beta)^\alpha}\ $$

Calculator

CDFWeibull(,,)

Graph

CDFWeibull function
Function: CDFWeibull(,,)
  X-axis Y-axis
Minimum:
Maximum:
 

RndWeibull(alpha,beta)

RndWeibull(alpha,beta) returns a random number of the Weibull distribution with parameters alpha and beta.

Calculator

RndWeibull(,)

See also