My name is Ezequiel D. Antokoletz. I am a PhD student from Argentina.
First of all, thank you very much for providing GMT for users, it is a very useful tool! I am writing you as I might find an issue with grdgradient under Windows x64 GMT v6.1.1. When trying to build the out_gridfile with the option -G, no file is created. I have tried with several extensions and none of them is working. When going back to GMT v6.0.0 no problem appears.
Best regards and thank you very much,