LOWPASS Forumla

In the 2.8 docs for lowpass the following formula is given when you paste the formula into a spreadsheet.

However no explanation of what e^ is so I can't complete the formula and match the example so I know if I'm correct or not.

Also on the man page it shows up like this: I assume that is a man page issue and I'll look into that when I return home.

Thanks to who added the examples but I wonder why the examples were not added to the 2.7 documents?

JT

the ^ and ** are both exponentiation operators
so e**n and e^n mean the same thing
( the constant e (2.71828...) raised to the power n )

Ah Ha, a little googling and I found this page on e



And now with that bit of information I'm able to complete the equation and it matches Deweys examples.

Thanks Peter

JT

Funny, we were both struggling with this at the same time. On another thread, Peter said for a 70 Hz filter the gain was:

PCW wrote: Rod:

0.355849556024592

( 1-e^(-2*pi*70*.001) )

(assuming 1 KHz sampling)

In my case, I had correctly assumed e = 2.718 but was let down by a crappy calculator on my Chromebook. Once I moved to Google Sheets, it was perfect! Thanks for the tip on spreadsheets John!

It would be good if the docs were updated to state:
where:
e = the mathematical constant 2.71828
and the more normal ^ symbol was used for yⁿ instead of ** (which I've never seen in use)

I found this interesting:
softwareengineering.stackexchange.com/qu...ad-of-exponentiation

I think that it was ** in Sinclair basic because the Sinclair character set didn't have ^

If I was in charge I think I might commonise on ** (super-multiplication).

Though that wouldn't work with C, it would have no way to know if a ** b meant "a to the power of b" or "a • the contents of b"

Pi has an infinite number of non-repeating decimal places.

e has an infinite number of non-repeating decimal places.

i is an imaginary number.

Yet e^i.pi = -1

Which is remarkable.
en.wikipedia.org/wiki/Euler's_identity