Exponential distribution with scale a, possibly time-dependent.
Wraps scipy.stats.expon(scale=a)
.
The probability distribution function is:
- if
a > 0
, pdf(x) = a*exp(-a*x)
, with support in [0, inf)
- if
a < 0
, pdf(x) = -a*exp( a*x)
, with support in (-inf, 0]