reflection: Reflection and folding of a function about zero
In pi0: Estimating the Proportion of True Null Hypotheses for FDR

Description Usage Arguments Details Value Author(s) Examples

reflect reflects the function defined on the nonnegative real line about zero to get a function defined on the whole real line, and then divide it by 2. fold folds a function defined on the whole real line at zero to get a function defined only on the non-negative real line.

1 2	reflect(f, ...) fold(f, ...)

`f`	the function to be reflected or folded
`...`	other arguments passed to `f`

See examples.

the new function

Long Qu

## reflect function is currently defined as
    function(x,...) ifelse(x>0, f(x,...), f(-x,...))/2

## fold function is currently defined as
    function(x,...) ifelse(x>=0, f(x,...)+f(-x,...), 0)

## double exponential pdf
ddexp=reflect(dexp)

## folded normal pdf
dfnorm=fold(dnorm)