Uses a bisectioning algorithm to search the give interval for a
change of sign and returns the integer which is closest to 0. When
extendInt is "upX" (f increasing through the root) or "downX"
(f decreasing), a bracket that does not enclose a sign change is
widened outward (doubling), bounded by clamp, until it brackets a
root. If no sign change exists within clamp, the constant sign is
reported as -Inf (f < 0) or Inf (f > 0); with extendInt = "no"
the legacy empty numeric() is returned instead.
uniroot_int(
f,
interval,
...,
f.lower = f(interval[1], ...),
f.upper = f(interval[2], ...),
extendInt = c("no", "upX", "downX"),
clamp = interval,
maxIter = 1000
)