#
# Note that the file, world.gdp.capita.10000BCE-2000.fraction-a, is
# the fractional increase in the GDP per capita, (and can have
# negative numbers,) and, if it contained data from a perfect
# exponential function would be a time series of constant numbers.
#
# The question is, since the GDP per capita since 1600 has "noise," is
# whether the zero growth from 1950 to 2000 is "noise," in an
# exponential growth of the world GDP per capita, or the top of a
# logistic/parabolic function?
#
# The last 9 elements of the file,
# world.gdp.capita.10000BCE-2000.fraction-a, contain the data from
# 1600 through 2000:
#
# tsscalederivative world.gdp.capita.10000BCE-2000.fraction-a  | tail -9 | tsavg -p
# 0.000057
# tsscalederivative world.gdp.capita.10000BCE-2000.fraction-a  | tail -9 | tsmath -t -s 0.000057 | tsrms -p
# 0.000100
# tsscalederivative world.gdp.capita.10000BCE-2000.fraction-a  | tail -9 | tsmath -t -s 0.000057 | tail -1
# -0.000059
; 0.000059 / 0.000100
;       0.59
# sigma 0.59
# 0.277595324753477368
#
# The standard error is 1 / sqrt (9) = 1 / 3, so there is a 95% chance
# that the chance of the world GDP per capita is a logistic/parabolic
# function is between 0.277595324753477368 - (1 / 3) =
# -0.05573800857985596533, and, 0.277595324753477368 + (1 / 3) =
# 0.61092865808681070133.
#
# Meaning, there is about a 72% chance, (+/- 33% standard error,) that
# the world GDP per capita is an exponential function instead of a
# logistic parabolic function-at least for the foreseeable future.