unable to install on mac os version 10.13.3

[XiminLin]

error message when trying to run (devtools::install_github("larryleihua/randomForestFML")):

ld: warning: directory not found for option '-L/usr/local/gfortran/lib/gcc/x86_64-apple-darwin15/6.1.0'
ld: library not found for -lgfortran
clang: error: linker command failed with exit code 1 (use -v to see invocation)
make: *** [randomForestFML.so] Error 1
ERROR: compilation failed for package ‘randomForestFML’
* removing ‘/Library/Frameworks/R.framework/Versions/3.5/Resources/library/randomForestFML’
Error in i.p(...) : 
  (converted from warning) installation of package ‘/var/folders/8d/n163vg3d2zx7_650xhwwpvv00000gn/T//RtmpRXusT2/file656342e9efd7/randomForestFML_4.6-14.tar.gz’ had non-zero exit status

[larryleihua]

it seems that you need to install lgfortran package first. You can first update your devtools package and then try again; if does not work, you need to install lgfortran