# check.pdf: Check and Potentially Graph Probability Density Functions In lmomco: L-Moments, Censored L-Moments, Trimmed L-Moments, L-Comoments, and Many Distributions

## Description

This convenience function checks that a given probability density function (`pdf`) from lmomco appears to numerically be valid. By definition a `pdf` function must integrate to unity. This function permits some flexibility in the limits of integration and provides a high-level interface from graphical display of the `pdf`.

## Usage

 ```1 2 3``` ```check.pdf(pdf, para, lowerF=0.001, upperF=0.999, eps=0.02, verbose=FALSE, plot=FALSE, plotlowerF=0.001, plotupperF=0.999, ...) ```

## Arguments

 `pdf` A probability density function from lmomco. `lowerF` The lower bounds of nonexceedance probability for the numerical integration. `upperF` The upper bounds of nonexceedance probability for the numerical integration. `para` The parameters of the distribution. `eps` An error term expressing allowable error (deviation) of the numerical integration from unity. (If that is the objective of the call to the `check.pdf` function.) `verbose` Is verbose output desired? `plot` Should a plot (polygon) of the `pdf` integration be produce? `plotlowerF` Alternative lower limit for the generation of the curve depicting the `pdf` function. `plotupperF` Alternative upper limit for the generation of the curve depicting the `pdf` function. `...` Additional arguments that are passed onto the R function `integration` function.

## Value

An R `list` structure is returned

 `isunity` Given the `eps` is `F` close enough. `F` The numerical integration of `pdf` from `lowerF` to `upperF`.

W.H. Asquith

## Examples

 ``` 1 2 3 4 5 6 7 8 9 10``` ```lmrg <- vec2lmom(c( 100, 40, 0.1)) # Arbitrary L-moments lmrw <- vec2lmom(c(-100, 40,-0.1)) # Reversed Arbitrary L-moments gev <- pargev(lmrg) # parameters of Generalized Extreme Value distribution wei <- parwei(lmrw) # parameters of Weibull distribution # The Weibull is a reversed GEV and plots in the following examples show this. # Two examples that should integrate to "unity" given default parameters. layout(matrix(c(1,2), 2, 2, byrow = TRUE), respect = TRUE) check.pdf(pdfgev,gev,plot=TRUE) check.pdf(pdfwei,wei,plot=TRUE) ```

### Example output ``` "pdf function appears to integrate to unity"
\$isunity
 TRUE

\$F
 0.998

 "pdf function appears to integrate to unity"
\$isunity
 TRUE

\$F
 0.998
```

lmomco documentation built on March 14, 2020, 5:06 p.m.