WeibullDistribution





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Creates a Weibull distribution object (Continuous Distribution).

The density pdf=[a*b*pow(x, b-1)*exp(-a*pow(x,b))], where a, b and x are positive values.

The Weibull distribution has been used successfully in reliability theory.

For b=1, the Weibull density reduces to the exponential density.

The string 'Key' resulting from a successful construction of this distribution object can be passed to the following functions in order to query (mean, std deviation and variance) or execute functions (probability function, cumulative density function etc...) based on this distribution object : CDistributionMean(), CDistributionVar(), CDistributionSTD(), CDistributionPDF(), CDistributionCDF(), CDistributionICDF() or CDistHazard(). In addition, the string 'Key' resulting from a successful construction of this distribution object will also allow you to construct a process generator object via a call to PGWeibullDistribution(). A process generator object allows you to generate large amounts of random numbers based on this distribution.

Even though PGWeibullDistribution() is the process generator object, the function RandomWeibull() is the actual function that obtains the random numbers given a count parameter and the process generator string 'key'.



This function creates an object and returns a string-key value to represent this created object.
The TAG value of the string-key returned (second part of the key) is : "Weibull"



Note: Within Excel, the function is named - CT.STAT.WeibullDistribution




High level graphic of WeibullDistribution() function with parameters. Blue square node is the actual function with the parameters ordered.



Parameter Description


  1. Key parameter

    Key value to use as a handle for the created object
  2. Reload parameter

    When creating this object for the first time, set this parameter to a positive value. Within Excel, when re-computing a worksheet where you do not wish to recreate the object, set this parameter to zero (0).
  3. scale parameter

    scale parameter (a).
  4. shape parameter

    shape parameter (b).


Extended information

Function Syntax

VB Syntax


String CTStatDistributions.WeibullDistribution( _
String Key, _
Long Reload, _
Double scale, _
Double shape)


Excel Spreadsheet Syntax


=CT.STAT.WeibullDistribution(
Excel String Cell Key,
Excel Numeric Cell Reload,
Excel Numeric Cell scale,
Excel Numeric Cell shape)


C++ Syntax


static std::string WeibullDistribution(
std::string Key,
long Reload,
double scale,
double shape);


DotNET Syntax


System.String CTStatDistributionsSA.WeibullDistribution(
System.String Key,
System.Int32 Reload,
System.Double scale,
System.Double shape);

Parameter data types

ArgNameArgTypeIsKey
KeyStringFALSE
ReloadLongFALSE
scaleDoubleFALSE
shapeDoubleFALSE


Example Inputs

The first column represents the name of the parameters. The second column specifies whether the parameters are optional or not. Finally the last column provides some sample input data.
Function call input string-keys are always in the format : "NAME.EXTTAG.TICKER" The "EXTTAG.TICKER" part is determined from the output of other, capetools, object creation functions.


ArgNameIsOptional (Excel only)Example
KeyFALSEMyWeibullDistribution
ReloadFALSE1
scaleFALSE1.0
shapeFALSE1.0


Example function usage


The C# example below contains all the sub-function calls leading up to this function call. As a result, the example can contain a lot of code.

The VB.NET, J#, C++.NET, Java, Excel VBA, Visual Basic 6 (via COM) and C++ examples below contain function code stubs for the calls leading up to this function call. However, the function call for this function is displayed.
You can easily reproduce the stub functions code from the C# example.


If you are accessing this functrion via the MiniXL libraries, this function is present within the CT.QL.Statistics20 MiniXL Excel Addin.

Within our Excel Example Addin Generator, we have used the following QuantTools sub-functions in order to prepare the arguments needed to call the WeibullDistribution() function. If you are executing this function via the MiniXL libraries, the module addin name, (in brackets, to the right of the sub-functions listed below), indicates the MiniXL library in which the sub-function is held. You will need to load this library into your Excel session (along with any other libraries that the sub-function call within the addin requires (ie - CT.QT.Utils20 addin in almost all cases) in order for the example to compute successfully.


The following four examples demostrate calling this function within a Microsoft .NET environment

The following four examples demostrate calling this function within a non .NET environment

The following is a sample output from executing the WeibullDistribution() function call


MyWeibullDistribution_18.Weibull.0

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