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This is a bit of a known error, where the compiler flag for including that Eigen.hpp file isn’t in quotations, so filenames with spaces cause an error. You can see this in your output:
“g++.exe: error: Graham/Documents/R/win-library/4.0/StanHeaders/include/stan/math/prim/mat/fun/Eigen.hpp
Where the filename starts with ‘Graham’, rather than ‘C:/Users/Patrick Graham’.
One workaround is to not load the RStan library, and just use the rstan:: qualifier instead.
So rather than:
library(rstan)
stan(model, data)
Use:
rstan::stan(model, data)
As this causes the Eigen.hpp file to be included in a different way (more info here)