Slightly easier to use - I've now added Low and High pass filters (you will almost certainly need to move the cut off values down). A value of zero will return the original data. I've included the executable in the zip file too.
As the functionality is rather useful - I've also added the ability to put the points on the command line as the first argument (comma separated, no spaces and no validation
).
I'm fairly impressed with Stephen Butterworth - the filters are clever given what was known in the 1930s (actually there just clever full stop).