f_slow = 4e-05 yr^-1 = 1/25000 yr
<- lower frequencies (larger periods) than this have to be PRESERVED!

passband_A <=> f/f_sampling < 0.005
stopband_A <=>              > 0.05
passband_B <=> f/f_sampling < 0.05
stopband_B <=>              > 0.15
ripple_A = 3.5e-05	, suppress_A = 1e-05
ripple_B = 1e-09	, suppress_B = 1e-09
========================================================================
dt0 = 1 yr, f_sampling0 = 1 yr^-1
filter no. 1 = A
decimation factor K1 = 10
f_slow = 4e-05 yr^-1 < passband_A * f_sampling0 = 0.005 yr^-1
Passband check passed OK.

f_max0 = 0.05 yr^-1 = 1/20 yr
dt1 = 10 yr
f_sampling1 = 0.1 yr^-1 > f_slow + f_max0 = 0.05004
Aliasing check passed OK.

------------------------------------------------------------------------
dt1 = 10 yr, f_sampling1 = 0.1 yr^-1
filter no. 2 = A
decimation factor K2 = 10
f_slow = 4e-05 yr^-1 < passband_A * f_sampling1 = 0.0005 yr^-1
Passband check passed OK.

f_max1 = 0.005 yr^-1 = 1/200 yr
dt2 = 100 yr
f_sampling2 = 0.01 yr^-1 > f_slow + f_max1 = 0.00504
Aliasing check passed OK.

------------------------------------------------------------------------
dt2 = 100 yr, f_sampling2 = 0.01 yr^-1
filter no. 3 = B
decimation factor K3 = 3
f_slow = 4e-05 yr^-1 < passband_B * f_sampling2 = 0.0005 yr^-1
Passband check passed OK.

f_max2 = 0.0015 yr^-1 = 1/666.667 yr
dt3 = 300 yr
f_sampling3 = 0.00333333 yr^-1 > f_slow + f_max2 = 0.00154
Aliasing check passed OK.

------------------------------------------------------------------------

========================================================================
final sampling timestep dt = 300 yr

final passband <=> f < 0.0005 yr^-1 <=> P > 2000 yr
total ripple in the passband = 7.0001e-05

final stopband <=> f > 0.0015 yr^-1 <=> P < 666.667 yr
minimum suppression in the stopband = 1e-09