Re: [gxnet]: GRIDTRND.GX

[Telma Aisengart]

Dear Emilson,   The problem is that if you want to remove a 2nd order trend you need six coefficients. If you specify only one coefficient this means you are removing a zero order trend - in other words a constant. If you want, you can leave blank the coefficients as the program will return the best fit surface calculated with least squares. I believe you specified 6 as the total numbers of coefficients needed but if you check the Help, that line is for the values of the 6 coefficients (for example: A1, B1, C1, A2, B2, C2).   Also note that this list - gxnet is for the gx developers. There is another list  - geonet ([EMAIL PROTECTED]) that is an Users List.   You can also ask directly for support through our office based in Brasil and we will very happy to assist you.   Best regards,   Telma Aisengart Santos Technical Manager   [EMAIL PROTECTED] Geosoft Latinoam�rica Ltda. Av. Rio Branco, 156  Gr. 2615 - Centro Rio de Janeiro - RJ - BRASIL CEP 20043-900 Tel: 55 21 532 - 0140 - Fax: 55 21 532 - 7197 Software and services for effective earth science decision-making. Free Oasis montaj interface now available at www.geosoft.com   ----- Original Message ----- From: Emilson Leite To: [EMAIL PROTECTED] Sent: Friday, January 26, 2001 10:31 AM Subject: [gxnet]: GRIDTRND.GX Hello friends, I'm a new user of Geosoft 5.05 and I'm trying to use the procedure GRIDTRND.GX, to remove a trend from a grid of gravimetric data. But I have a problem in the results.   The parameters that I'm using use are: input grid file: arlivre.grd output grid file with trend removed: arlivre_resid.grd points to use: ALL Order to Remove: 2 Coefficients of removed polynomial: 6 Replace previously removed trend?: NO   When I display the residual grid (arlivre_resid.grd) I can see that the grid is the same of original grid (arlivre.grd) and it's shouldn't occur. The polynomial trend are not a constant value surface! Well, maybe I made a mistake in parameters but I don't think so.   Thank you, Emilson P. Leite