# RtoDPQ

From distr v2.2.3
by Peter Ruckdeschel

##### Default procedure to fill slots d,p,q given r for a.c. distributions

function to do get empirical density, cumulative distribution and quantile function from random numbers

- Keywords
- distribution, arith, math

##### Usage

`RtoDPQ(r, e = getdistrOption("RtoDPQ.e"), n = getdistrOption("DefaultNrGridPoints"))`

##### Arguments

- r
- the random number generator
- e
- $10^e$ numbers are generated, a higher number leads to a better result.
- n
- The number of grid points used to create the approximated functions, a higher number leads to a better result.

##### Details

RtoDPQ generates $10^e$ random numbers, by default $$e = RtoDPQ.e$$. The density is formed on the basis of $n$
points using approxfun and density, by default $$n = DefaultNrGridPoints$$.
The cumulative distribution function and the quantile function are also created on the basis of $n$ points using
`approxfun`

and `ecdf`

. Of course, the results are usually not exact as they rely on random numbers.

##### Value

`RtoDPQ`

returns a list of functions.dfun density pfun cumulative distribution function qfun quantile function

##### Note

Use `RtoDPQ`

for absolutely continuous and `RtoDPQ.d`

for discrete distributions.

##### concept

- random sample
- image distribution
- absolutely continuous distribution
- utility

##### See Also

##### Examples

```
rn2 <- function(n){rnorm(n)^2}
x <- RtoDPQ(r = rn2, e = 4, n = 512)
# returns density, cumulative distribution and quantile function of
# squared standard normal distribution
x$dfun(4)
RtoDPQ(r = rn2, e = 5, n = 1024) # for a better result
rp2 <- function(n){rpois(n, lambda = 1)^2}
x <- RtoDPQ.d(r = rp2, e = 5)
# returns density, cumulative distribution and quantile function of
# squared Poisson distribution with parameter lambda=1
```

*Documentation reproduced from package distr, version 2.2.3, License: LGPL-3*

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