`directional_inverse.Rd`

Calculates the smallest value for which a function `f`

evaluates to be greater than or equal to `y`

-- that is,
the left inverse of `f`

at `y`

. Intended for internal use only.

`directional_inverse(distribution, p, low, high, tol, maxiter, direction)`

- distribution
A distribution having access to a cdf.

- p
Single value for which to calculate the left inverse.

- low, high
Single numeric values forming a range within which to search for the solution.

- tol, maxiter
Tolerance (a small positive number) and maximum number of iterations

- direction
One of

`"left"`

for calculating left-inverse, or`"right"`

for calculating right-inverse.

This algorithm works by progressively cutting the specified range in half, so that the width of the range after k iterations is 1/2^k times the original width.