RE: [geonet]: Least squares filter

[Lorraine Godwin]

Here are the references for the Least Squares Filter: If anyone wants to know how C:\GEOSOFT\ETC\LEASTSQU.5X5 coefficients are derived in detail, please refer to the following references: Savitzky A. and Golay M., 'Smoothing and differentiation of data by simplified least squares procedures', Analytical Chemistry 36 (1964) no. 8, pp1627-1639. Press W. etc. 'Numerical Recipes in C: The art of scientific computing', Cambridge Univ. Press, 2nd ed. 1992, (Savitzky-Golay Smoothing Filters, pp650-655) Cheers, Ting Geosoft Inc. -----Original Message----- From: Lorraine Godwin [mailto:[EMAIL PROTECTED]] Sent: Thursday, January 31, 2002 10:06 AM To: '[EMAIL PROTECTED]' Subject: RE: [geonet]: Least squares filter Hi everyone,   Ting Dai, one of our senior geophysicists here, replied offline to Aaron on this question but I thought I would post it in case anyone else was interested.   Cheers, Lorraine Hi, Aaron, C:\GEOSOFT\ETC\LEASTSQU.5X5 coefficients are derived from least square fitting to order=2 curved surface a00+a10x+a01y+a11xy+a20x^2+a02y^2 with 25 points data (z22, z21, …z00, … z-2-2). Please contact me if there are any further queries. Cheers, Ting Geosoft Inc.    -----Original Message----- From: skyhunter [mailto:[EMAIL PROTECTED]] Sent: Wednesday, January 30, 2002 12:36 PM To: GEONET Subject: [geonet]: Least squares filter Hi everyone,   I was wondering if anyone can give me any information on the least squares convolution filters that appear in the file C:\GEOSOFT\ETC\LEASTSQU.5X5. Specifically, were did it come from, how was it derived.   Aaron Balasch Sky Hunter Technologies Inc. Suite 101, 1725 10th Avenue S.W. Calgary, Alberta T3C 0K1 email: [EMAIL PROTECTED] phone: 403-228-2175 fax: 403-244-7955