From: Bret Cahill on
Two functions, sin(x) and sin(x + phi), are separated by a small phase
angle.

The different between the functions, sin(x) - sin(x + phi) can be
approximated by phi times the derivative of sin(x) = phi cos(x).

Will this work for all waveforms separated by a small phase angle?


Bret Cahill


From: Narasimham on
On Aug 10, 7:25 pm, Bret Cahill <BretCah...(a)peoplepc.com> wrote:
> Two functions, sin(x) and sin(x + phi), are separated by a small phase
> angle.
>
> The different between the functions, sin(x) - sin(x + phi)  can be
> approximated by phi times the derivative of sin(x) = phi cos(x).

The difference between the functions, sin(x) - sin(x - phi)  can be
approximated by phi times the derivative of sin(x) = phi cos(x).

> Will this work for all waveforms separated by a small phase angle?
>
> Bret Cahill

Yes, phi f'(x). that is the definition of derivative.

Narasimham
From: Tim Little on
On 2010-08-10, Bret Cahill <BretCahill(a)peoplepc.com> wrote:
> The different between the functions, sin(x) - sin(x + phi) can be
> approximated by phi times the derivative of sin(x) = phi cos(x).
>
> Will this work for all waveforms separated by a small phase angle?

If the waveform is differentiable, yes. That property (when
formalized) is actually the definition of the derivative.


- Tim
From: Bret Cahill on
Thanks.


Bret Cahill