Step (piecewise-constant) PMF

Returns the probability mass for each value in x. Mass pmf[i] is located at boundaries[i+1] (the right edge of bin i); all other values return 0.

Usage

ddiscretestep(x, boundaries = NULL, pmf)

Arguments

x

Numeric vector of values at which to evaluate the PMF.

boundaries

Numeric vector of length \(K+1\) defining the bin edges. Must be strictly increasing. Defaults to 0:K (unit-width daily bins) where K is inferred from length(pmf).

pmf

Numeric vector of length \(K\) giving the probability mass for each bin. Must be non-negative and sum to approximately 1; if either condition is violated the function returns a vector of .Machine$double.eps rather than 0 (a soft simplex penalty that keeps log-density finite inside fitting closures).

Value

Numeric vector of PMF values, the same length as x.

Details

Like pdiscretestep, this function applies a soft simplex penalty: if pmf contains negative entries or fails to sum to 1 (within \(10^{-8}\)), the function returns near-zero density (.Machine$double.eps) rather than erroring. This makes it safe to call from inside fitdistrplus::fitdist() closures driven by fitdistdoublecens.

See also

Other pdiscretestep: hazards_to_pmf(), pdiscretestep(), pmf_to_hazards(), rdiscretestep()

Examples

ddiscretestep(c(0, 1, 2, 3), boundaries = 0:3, pmf = c(0.2, 0.5, 0.3))
#> [1] 0.0 0.2 0.5 0.3