[mathcad] RE: Sinus regression using genfit

Author: Pergande, Albert N Posted: Wed, 15 Feb 2006 14:14:16 -0500

You might try an fft - re- multiply so it's a*sin(bx+c)+d. The 0 bin is
d, the bin number of the peak is b, the magnitude of the peak is a (plus
or minus a 2 pi or an "N") and the phase you can estimate once you know
the frequency. Should work if you have a full cycle or more.

Al Pergande
Senior Radar Engineer
Lockheed Martin Missiles and Fire Control
MP 200
5600 Sandlake Road
Orlando, Fl 32819

Voice 407-356-5169
Fax 407-356-0933
"albert.n.pergande"
for personal mail - "al"

From: Torgrim Sandvoll "mailto:torgrim"
Sent: Wednesday, February 15, 2006 12:13 PM
To: Mathcad Discussion List
Subject: [mathcad] Sinus regression using genfit

Hi,

Trying to fit the general function: f(x,a):a0*sin(a1*(x+a2))+a3

(See attached Mathcad (v11+) document)

Have tried with genfit, but this method seems very sensitive to the
guess values given.

Any better way to solve this problem would be appreciated!

Have a nice day! :-)

Best regards,
Torgrim Sandvoll

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