fixed derivative issue, but why?
fixed derivative issue, but why?

saikanth88/femus,FeMTTU/femus,FeMTTU/femus,giorgiobornia/femus,saikanth88/femus,giorgiobornia/femus,FeMTTU/femus,giorgiobornia/femus,saikanth88/femus,FeMTTU/femus,saikanth88/femus,giorgiobornia/femus