Calculate the p-norm of any function between given limits.

`generalPNorm(fun, p, lower, upper, range = NULL)`

## Arguments

- fun
function to calculate the p-norm of.

- p
the pth norm to calculate

- lower
lower bound for the integral

- upper
upper bound for the integral

- range
if discrete then range of the function to sum over

## Value

Returns a numeric value for the p norm of a function evaluated between given limits.

## Details

The p-norm of a continuous function \(f\) is given by,
$$(\int_S |f|^p d\mu)^{1/p}$$
where \(S\) is the function support. And for a discrete function by
$$\sum_i (x_{i + 1} - x_i) * |f(x_i)|^p$$
where \(i\) is over a given range.

The p-norm is calculated numerically using the `integrate`

function and therefore results
are approximate only.

## Examples

```
generalPNorm(Exponential$new()$pdf, 2, 0, 10)
#> Results from numeric calculations are approximate only. Better results may be available.
#> [1] 0.7071068
```