How to calculate total horizontal gradient for a grid

Objective:

I would like to calculate the Total Horizontal Gradient for a Geosoft grid (*.grd).

Resolution:

Here are the steps to compute the Total Horizontal Derivative, which is √ dx² + dy²

To compute this in Geosoft you need to do the following:

1. Take the X derivative, Grid and Image menu > Filters > Horizontal Gradient… use gradient direction as 0.
2. Take the Y derivative, Grid and Image menu > Filters > Horizontal Gradient… use gradient direction as 90.
3. Calculate the Total Horizontal Gradient, Grid and Image menu > Grid Math > Expression: G3=SQRT((G1*G1)+(G2*G2)).
   Enter the grid from step 1 as G1, the grid from step 2 as G2 and enter a new grid name for G3 (this will be your Total Horizontal Gradient grid). 
   
   You may want to convert this to degrees in which case you’d have to use the following expression:
   G3=(ATAN(G0))*180/3.14159265
   Where G3 is the output grid in degrees and G0 is the grid that was calculated from the DX and DY grids.

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