Psmask warnings

Hi everyone,

I have been using GMT to create frequency heat maps for my R package, SSHAARP. I’ve used versions >=6.1.1 without triggering any warning messages. However, with version 6.2.0, I’m getting these warning messages for psmask:

psmask [WARNING]: (y_max-y_min) must equal (NY + eps) * y_inc), where NY is an integer and |eps| <= 0.0001.
psmask (gmtapi_init_grdheader): Please select compatible -R and -I values

Here is my code:
gmt psmask -R-180/180/-60/80 -I3 -JM6i -S850k -O -K

Does anyone have some insight as to what these warnings mean, and what I need to change in the psmask parameters to make the warnings stop?

Thank you!

Well, your increment 3 does not fit nicely into the range from -60 to 80. That is a range of 140 and 140/3 is not an integer. -60/81 would work, as would -61/80 I think.