grdgradient -S says: *Name of output grid file with scalar magnitudes of gradient vectors.*

Does this mean that output is in radians?

grdgradient -S says: *Name of output grid file with scalar magnitudes of gradient vectors.*

Does this mean that output is in radians?

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No. Gradient magnitude is in z-data-units/horizontal distance.

Thanks Paul.

So in order to get the degree of slope, I could take `arctan(z-data-units/horizontal distance)`

(based on this)?

Are there any gmt-utilities that can do this for me directly, or do I have to use some `grdmath`

RPN magic?

So slope only makes sense for DEMs. For other data types there is no “angle”, just things like mGal/km. If you converted to flat Earth scaling (via -fg) then I think the gradients for a DEM will be in meters/km and you would need to scale it by 0.001 to get dimensionless tangents and then inverse tangent to get the angle.

Try this to get a slope grid in degrees.

```
gmt grdmath $GRD ATAND = $SLP
```

`grdgdal`

says it can do it.

**-A** *prog*[**+m** *method* **+c** *cpt*]

Select which GDAL program to run (currently one of *info*, *dem*, *grid*, *rasterize*, *translate* or *warp*). When program is *dem* then please append **+m** *method* (pick one of *hillshade*, *color-relief*, **slope**, *TRI*, *TPI* or *roughness*)

Thank you all for tips and comments. Will test.