CRAN policies - citing others

Dear R users,

we try to submit a package to CRAN. One of our function pbcOptim.R uses lbfgsb.cpp which is a slight modification of optim.c. In the documentation for pbcOptim.R we said

"The code for pbcOptim is based on that of \code{\link{optim}}. In particular, pbcOptim calls /src/lbfgsb.cpp which is a slight adaptation of lbfgsb.c and optim.c part of the R software (http://www.r-project.org/). See \code{\link{optim}} and ?optim."

However, CRAN responded that we were not the authors of lbfgsb.cpp and we did not mention them. Do we have to spell their names explicitely? In the documentation for pbcOptim.R? In the file DESCRIPTION? In the file lbfgsb.cpp?

Thanks you very much for your help

Gildas Mazo
PhD student
MISTIS team at INRIA
Grenoble, France