make: gfortran: No such file or directory<br>
make: *** [variogram.o] Error 1<br>
ERROR: compilation failed for package ‘sm’<br>
* removing ‘/Library/Frameworks/R.framework/Versions/3.5/Resources/library/sm’<br>
已经下载了gfrotran和xcode了还是出现这种问题,求大神指点<br>