[ferret_users] low pass filter

[Sandeep Mohapatra <sandeepmohapatra21@xxxxxxxxx>]

Hi,

I have gone through the low pass filter concept mentioned in ferret.

suppose i have monthly data of 696 months, 
i want to calculate 10 yr low pass filter.
And  I use the below fomula 

var1 = lsl_lowpass(var,696,121)

So, I just want to know whether this method is correct or not.

if not, please tell me the correct method.