Derivatives on HP 42S
08-26-2018, 08:39 PM
Post: #23
 Albert Chan Senior Member Posts: 1,897 Joined: Jul 2018
RE: Derivatives on HP 42S
(08-26-2018 04:47 PM)lrdheat Wrote:  When I run dx for, say, pi/4 (let's be simple and use fx=sin x), I get ~0 instead of ~.707

my guess is you forget to divide by h:

df(x) ~ Im((f(x + i*h)) / h

Code:
>>> from cmath import * >>> h = 1e-6 >>> sin(complex(pi/4, h).imag 7.0710678118666542e-07 >>> _ / h 0.70710678118666548
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 Messages In This Thread Derivatives on HP 42S - lrdheat - 08-20-2018, 03:03 AM RE: Derivatives on HP 42S - Thomas Klemm - 08-20-2018, 04:38 AM RE: Derivatives on HP 42S - Thomas Klemm - 08-20-2018, 07:43 AM RE: Derivatives on HP 42S - Albert Chan - 08-20-2018, 11:54 PM RE: Derivatives on HP 42S - lrdheat - 08-20-2018, 10:57 PM RE: Derivatives on HP 42S - Thomas Klemm - 08-20-2018, 11:43 PM RE: Derivatives on HP 42S - Thomas Klemm - 08-21-2018, 12:34 AM RE: Derivatives on HP 42S - Thomas Klemm - 08-21-2018, 01:35 AM RE: Derivatives on HP 42S - lrdheat - 08-21-2018, 02:24 AM RE: Derivatives on HP 42S - Thomas Klemm - 08-21-2018, 06:14 AM RE: Derivatives on HP 42S - RMollov - 08-23-2018, 12:58 PM RE: Derivatives on HP 42S - lrdheat - 08-24-2018, 02:51 AM RE: Derivatives on HP 42S - Thomas Klemm - 08-24-2018, 05:52 AM RE: Derivatives on HP 42S - lrdheat - 08-25-2018, 05:19 PM RE: Derivatives on HP 42S - Albert Chan - 08-25-2018, 07:03 PM RE: Derivatives on HP 42S - Thomas Klemm - 08-25-2018, 06:05 PM RE: Derivatives on HP 42S - Thomas Klemm - 08-25-2018, 08:00 PM RE: Derivatives on HP 42S - Albert Chan - 08-25-2018, 09:20 PM RE: Derivatives on HP 42S - Thomas Klemm - 08-26-2018, 04:54 AM RE: Derivatives on HP 42S - Thomas Okken - 08-26-2018, 01:54 PM RE: Derivatives on HP 42S - lrdheat - 08-26-2018, 04:47 PM RE: Derivatives on HP 42S - Albert Chan - 08-26-2018 08:39 PM RE: Derivatives on HP 42S - Thomas Klemm - 08-26-2018, 08:00 PM RE: Derivatives on HP 42S - Albert Chan - 08-29-2018, 01:52 PM

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