$ perl trend.t
slow_increase distribution, constant 0, slope 0, error 0
random distribution, constant 0, slope 0, error 0
fast_increase distribution, constant 0, slope 0, error 0
not ok 1 - $slow_increase_error < $random_error
#   Failed test '$slow_increase_error < $random_error'
#   in trend.t at line 96.
not ok 2 - $fast_increase_error < $random_error
#   Failed test '$fast_increase_error < $random_error'
#   in trend.t at line 97.
not ok 3 - $slow_increase_slope < $fast_increase_slope
#   Failed test '$slow_increase_slope < $fast_increase_slope'
#   in trend.t at line 102.
1..3
# Looks like you failed 3 tests of 3.
$