WEIBULL

Returns the Weibull distribution. Use this distribution in reliability analysis, such as calculating a device's mean time to failure.

Syntax

WEIBULL(x,alpha,beta,cumulative)

X   is the value at which to evaluate the function.

Alpha   is a parameter to the distribution.

Beta   is a parameter to the distribution.

Cumulative   determines the form of the function.

Remarks

• If x, alpha, or beta is nonnumeric, WEIBULL returns the #VALUE! error value.
• If x < 0, WEIBULL returns the #NUM! error value.
• If alpha £ 0 or if beta £ 0, WEIBULL returns the #NUM! error value.
• The equation for the Weibull cumulative distribution function is:

  

• The equation for the Weibull probability density function is:

  

• When alpha = 1, WEIBULL returns the exponential distribution with:

  

Examples

WEIBULL(105,20,100,TRUE) equals 0.929581

WEIBULL(105,20,100,FALSE) equals 0.035589